Alkyl Chain Engineering of SolutionProcessable ...

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Jie Min,* Yuriy N. Luponosov, Andreas Gerl, Marina S. Polinskaya, Svetlana M. Peregudova, Petr V. Dmitryakov, Artem V. Bakirov, Maxim A. Shcherbina, Sergei N. Chvalun, Souren Grigorian, Nina Kaush-Busies, Sergei A. Ponomarenko, Tayebeh Ameri, and Christoph J. Brabec

The impact of alkyl side-chain substituents on conjugated polymers on the photovoltaic properties of bulk heterojunction (BHJ) solar cells has been studied extensively, but their impact on small molecules has not received adequate attention. To reveal the effect of side chains, a series of star-shaped molecules based on a triphenylamine (TPA) core, bithiophene, and dicyanovinyl units derivatized with various alkyl end-capping groups of methyl, ethyl, hexyl and dodecyl is synthesiyed and studied to comprehensively investigate structure-properties relationships. UV-vis absorption and cyclic voltammetry data show that variations of alkyl chain length have little influence on the absorption and highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) levels. However, these seemingly negligible changes have a pronounced impact on the morphology of BHJ thin films as well as their charge carrier separation and transportation, which in turn influences the photovoltaic properties of these small-molecule-based BHJ devices. Solution-processed organic solar cells (OSCs) based on the small molecule with the shortest methyl end groups exhibit high short circuit current (Jsc) and fill factor (FF), with an efficiency as high as 4.76% without any post-treatments; these are among the highest reported for solution-processed OSCs based on star-shaped molecules.

J. Min, A. Gerl, T. Ameri, C. J. Brabec Institute of Materials for Electronics and Energy Technology (I-MEET) Friedrich-Alexander-University Erlangen-Nuremberg Martensstraße 7, 91058, Erlangen, Germany E-mail: [email protected] Y. N. Luponosov, M. S. Polinskaya, P. V. Dmitryakov, A. V. Bakirov, M. A. Shcherbina, S. N. Chvalun, S. A. Ponomarenko Nikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences Profsoyuznayast. 70, Moscow, 117393, Russia S. M. Peregudova Nesmeyanov Institute of Organoelement Compounds Russian Academy of Sciences Vavilova St. 28, Moscow, 119991, Russia

DOI: 10.1002/aenm.201301234

Adv. Energy Mater. 2014, 4, 1301234

1. Introduction Bulk heterojunction (BHJ) organic solar cells (OSCs) based on small molecules as donor materials have attracted extensive attention due to their numerous advantages, which include well-defined molecular structure, easy purification, easy mass-scale production, high charge carrier mobility, and better batch-to-batch reproducibility.[1–4] Recently, the power conversion efficiency (PCE) of the solution-processed small molecule (SM) OSCs has reached 7–8% via designing novel linear small molecules.[5,6] Most of small molecules as donor materials for photovoltaic applications normally contains four key constituent components: donor/ acceptor (D/A) units, conjugated bridges, heteroatom substitutions, and side chains. The creative design and choice of donor or acceptor units, conjugated bridges, and heteroatom substitutions has been successfully conquered the shortcomings

S. Grigorian Institute of Physics University of Siegen Emmy-Noether-Campus Walter-Flex-Str. 3, D-57068, Siegen, Germany N. Kaush-Busies Heraeus Precious Metals GmbH & Co. KG Conductive Polymers Division (Clevios) Chempark Leverkusen Build. B202, D-51368, Leverkusen, Germany S. A. Ponomarenko Chemistry Department Moscow State University Leninskie Gory 1–3, Moscow, 119991, Russia C. J. Brabec Bavarian Center for Applied Energy Research (ZAE Bayern) Haberstraße 2a, 91058, Erlangen, Germany

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Alkyl Chain Engineering of Solution-Processable Star-Shaped Molecules for High-Performance Organic Solar Cells

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of unbalanced charge transport and poor film quality of small molecule OSCs and driven their efficiency to record highs.[6–13] However, the side chains location and length have largely been overlooked until recently.[8,14–17] As we know, small molecules require side chains to ensure their solubility in the processing solvent prior to device fabrication, which is similar with the conjugated polymers.[18] However, compared to their polymeric counterparts, small molecule limited by the molecular weight (Mn) based device performance can easily and sensitively suffer from inadequate interconnectivity and inefficient charge extraction, resulting in lower photovoltaic properties of related OSCs (e.g., open circuit voltage, Voc, short circuit current, Jsc, and fill factor, FF).[8] Because of the lower Mn of small molecules, the percolated networks with continuous carrier transport pathways to electrodes form more difficultly. This trend also could be explained in terms of the morphology of molecular heterojunctions, where small molecules tend to disperse in the acceptor domains and not form intermolecular packing and thus result in morphologies with more charge-trapping “cul-de-sacs” and dead ends.[2,19] Recently, several works demonstrated that the grafting of different alkyl side chains onto small molecule can dramatically ameliorate intermolecular packing, morphology in blend, optoelectronic properties, and, consequently, photovoltaic performance.[8,14,15,20] For example, we have previously shown that suitable alkyl side chain position and length strengthen the absorption and decrease the highest occupied molecular orbital (HOMO), leading to an increased Voc, Jsc, and FF.[14] In addition, Peter and co-workers reported three dicyanovinyl (DCN)

based quarterthiophenes in which they varied alkyl chains at the terminal thiophene units from hydrogen to methyl and ethyl. Compared to the other two molecules, methyl based quarterthiophene in blend with fullerene C60 received the best efficiency in the series owing to enhanced Jsc and FF.[16] In this respect, carefully designing and controlling the position and density of different alkyl side or end chains of the conjugated oligomers can not only adjust suitable solubility of materials in organic solvents but also balance the band structure and morphology in the solid state, and thus improve their photovoltaic properties. Among the soluble organic photovoltaic small molecules, star-shaped molecules have been developed as an interesting class of semiconducting materials and used in OSCs because of a number of advantages.[21] By tailoring and substituting the functional groups including donor units, acceptor units, and conjugated bridge, star-shaped molecules can be designed to realize a low bandgap, strong and broad absorption, together with highly ordered and interconnected domains, resulting in improved PCE of devices.[22–25] However, the impact of respective alkyl chains on the star-shaped small molecule OSCs was not studied in sufficient detail. In order to determine the effect of alkyl chains on photovoltaic performance, we have designed and synthesized four triphenylamine (TPA) unit based star-shaped molecules (N(Ph2T-DCN-Me)3, N(Ph-2T-DCN-Et)3, N(Ph-2T-DCN-Hex)3, and N(Ph-2T-DCN-Dodec)3) with methyl, ethyl, hexyl and dodecyl as alkyl chains for investigating and understanding alkyl chain length-property relationships, as shown in Scheme 1. NC

NC

CN

CN S

S

NC

CN

CN S

S

NC

S

S

S

S

N N

S

N(Ph-2T-DCN-Me)3

N(Ph-2T-DCN-Et)3

S

S NC

S NC

NC

NC

NC NC

S

S

S

S

CN

CN

CN

CN NC

S S

NC

S

N

S N

N(Ph-2T-DCN-Hex)3

N(Ph-2T-DCN-Dodec)3

S

S

S NC

S

NC

NC NC

Scheme 1. Chemical structures of the TPA-DCN star-shaped molecules investigated.

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derivatives of the corresponding protected ketones 3a-d by lithiation of compounds 2a-d followed by the treatment with 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (IPTMDOB) was carried out. The fourth stage includes the synthesis of starshaped compounds 4a-d by the Suzuki cross-coupling between compounds 3a-d and tris(4-bromophenyl)amine. In the fifth stage, solutions of compounds 4a-d in tetrahydrofuran (THF) were treated with HCl to remove dioxolane protecting groups, resulting in poorly soluble star-shaped ketones 5a-d, which precipitate from the reaction mixture and can be collected by filtration in quantitative yield. Finally, N(Ph-2T-DCN-Me)3, N(Ph-2T-DCN-Et)3, N(Ph-2T-DCN-Hex)3 and N(Ph-2T-DCNDodec)3 were prepared by Knövenagel condensation reaction of compounds 5a-d with the excess of malononitrile in pyridine, which was used both as a base and as a solvent. Microwave heating of the Knövenagel condensation was found to decrease both the reaction time and the amount of by-products compared to conventional heating. Gel permeation chromatography (GPC), 1H-, and 13C-NMR spectroscopy, elemental analysis, and high-resolution massspectroscopy were used to characterize the structure of these molecules (see Supporting Information, Figure S1–S33). N(Ph2T-DCN-Et)3, N(Ph-2T-DCN-Hex)3, and N(Ph-2T-DCN-Dodec)3 were readily soluble in common organic solvents such as THF, chloroform, dichloromethane, and chlorobenzene. However, N(Ph-2T-DCN-Me)3 was found to be significantly less soluble at room temperature compared to its analogs with the longer alkyl chains. Thermal properties of the TPA-DCN star-shaped molecules synthesized were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Figure S34 (see Supporting Information) shows the results of thermogravimetric analysis of the studied compounds under nitrogen flow. One can see that the samples possess very good thermal stability, starting to decompose only above 350 °C. Coke residue

2. Results and Discussion 2.1. Synthesis and Characterization of the Star-Shaped Molecules The novel TPA-DCN star-shaped organic molecules (Scheme 1) were synthesized using a previously developed synthetic approach based on preparation of the star-shaped triketones followed by a Knövenagel condensation with malononitrile under a microwave irradiation.[14] This synthetic method avoids the free protons at the DCN groups, which may negatively influence the stability of such materials in organic solar cells. Synthesis of novel TPA-DCN molecules consists of six consecutive reaction stages as outlined in Scheme 2. First, the preparation of bithiophene ketone precursors by acylation of 2,2′-bithien-5-yl magnesium bromide, synthesized in situ from 5-bromo-2,2′-bithiophene and magnesium, with corresponding alkanoyl chloride, using lithium manganese chloride as a catalyst, was performed. Second, protected ketones 2a-d were synthesized by the reaction of compounds 1a-d with ethylene glycol in the presence of p-toluenesulfuric acid, which was used as a catalyst. Third, the preparation of pinacolineboronic

S

Br

1) Mg 2)RCOCl, Li2MnCl4

S

O O

O S

THF 0 - +23 oC

S

p-TosH, HO-CH2-CH2-OH R

S

85%

1 a-d

O

S B

R

S

benzene, reflux

O O

1) BuLi 2) IPTMDOB

O

THF -78 - +23 oC

2 a-d

3 a-d R

R O

O O

S

R

O

O

O S

R S

S

S

S S

S

N

N Br

Br N

R

S

3a-d

4

Pd(PPh3)4 toluene/ethanol reflux

5

HCl

a-d

NC

CN

N(Ph-2T-DCV-R)3

pyridine microwave heating, 105 0C

THF, reflux S

S

a *

Br

S

S O O

where R =

c *

O R

b *

R

d *

Scheme 2. Synthesis of the TPA-DCN star-shaped molecules with methyl, ethyl, hexyl, and dodecyl solubilizing end groups.




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Among the four star-shaped TPA-based small molecules, N(Ph2T-DCN-Me)3, which has methyl end groups, exhibited broadened absorption in the film, better morphology, and higher mobility in blends with PC70BM as well as longer charge carrier lifetime in the device. Solution-processed solar cells based on N(Ph-2T-DCN-Me)3:PC70BM (1:2, wt%) by doctor-blading, without any post-treatments, showed a PCE of 4.76% and a fill factor of 56%, under illumination of AM. 1.5 (100 mA cm−2). The PCE of 4.76% is the highest reported value for the OSCs based on the solution-processed star-shaped organic molecules.

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1.0

a

N(Ph 2T-DCN-Me)3 N(Ph 2T-DCN-Et)3 N(Ph 2T-DCN-Hex)3 N(Ph 2T-DCN-Dodec)3

0.5

1.0 Normalized absorbance (a.u.)

Normalized absorbance (a.u.)

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www.MaterialsViews.com N(Ph 2T-DCN-Me)3

b

N(Ph 2T-DCN-Et)3 N(Ph 2T-DCN-Hex)3

0.8

N(Ph 2T-DCN-Dodec)3

0.6 0.4 0.2 0.0

0.0 400

500

600

700

400

Wavelength (nm)

500

600

700

800

Wavelength (nm)

Figure 1. UV-vis absorption spectra of N(Ph-2T-DCN-Me)3, N(Ph-2T-DCN-Et)3, N(Ph-2T-DCN-Hex)3 and N(Ph-2T-DCN-Dodec)3 a) in ODCB solutions and b) in films.

gradually diminishes with increasing alkyl chain length and comparison of the weight losses at very high temperatures indicates unambiguously that this is due to decomposition of the aliphatic tails together with dicyano groups. Under the air flow all the compounds start to lose the weight at 300 °C completely decomposing without any residue at 650 °C (Figure S35, Supporting Information). In all compounds investigated, only a glass transition was observed in DSC scans (Figure S36, Supporting Information). Its temperature gradually decreases with increasing the length of the aliphatic tails from 151 to 31 °C, while the heat capacity jump ΔCp grows from 0.21 to 0.26 J g−1 K−1, respectively (Table S1, Supporting Information). Wide-angle measurements of X-ray scattering revealed that at room temperature all the samples do not possess any crystalline order. Only a wide halo was observed in the corresponding scattering curves (Figure S37, Supporting Information). However, two important features should be noted. The first is a comparatively narrow reflection on the curve of N(Ph2T-DCN-Et)3, corresponding to d-spacing of 5.49 Å, which could be ascribed to the remnants of the ordering of crystal solvates. The second is a substantially changed shape of the amorphous halo for the sample with the longest alkyl chain N(Ph-2T-DCNDodec)3. Moreover, in contrast to the other compounds investigated, which do not reveal any reflections in the small-angle X-ray scattering (SAXS) patterns (Figure S38, Supporting Information, curves 1 and 2), compound N(Ph-2T-DCN-Dodec)3 is characterized by a wide small-angle reflection corresponding to d-spacing of 30.3 Å (Figure S38, Supporting Information,

curves 3–5). The very wide halo on curves 1 and 2 of Figure S38 (Supporting Information) is possibly defined by the form-factor of rigid central parts of the individual molecules, which are identical for both compounds. Further discussion of small and wide X-ray scattering investigation of N(Ph-2T-DCN-Dodec)3 can be found in the Supporting Information. 2.2. Optical and Electrochemical Properties Figure 1 shows the UV-vis absorption spectra of dilute solutions of these four star-shaped small molecules in o-dichlorobenzene (ODCB) and thin films doctor bladed on quartz substrates. The absorption spectrum of the four TPA-based molecules in solutions show similar absorption peaks and regions, exhibiting a strong visible absorption peak at ca. 517 nm (see Figure 1a), which is attributed to the intramolecular charge transfer (ICT) transition between the TPA-bithiophene donor unit and the DCN acceptor unit. The absorption spectra of the thin films of all small molecules investigated (see Figure 1b) show a redshift compared to their solution spectra, which results from the aggregation of the molecules in the solid films. The detailed absorption data, including the absorption maxima wavelengths in solutions and thin films, the absorption edge of the thin films, and the optical bandgap deduced from the absorption edges, are summarized in Table 1. Although the four TPAbased molecules investigated have similar absorption spectra in solution, the red-shift of the film absorption spectra compared

Table 1. Optical and electrochemical properties of the TPA-stars. Small molecules

UV-vis absorption spectra solutiona)

Cyclic voltammetry filmb)

p-doping

n-doping

λmax [nm]

λmax [nm]

λonset [nm]

Egopt c) [eV]

φox/HOMO [V]/[eV]

φred/LUMO [V]/[eV]

EgEC [eV]

N(Ph-2T-DCN-Me)3

517

541

711

1.74

0.92/–5.32

–0.99/–3.41

1.91

N(Ph-2T-DCN-Et)3

517

525

663

1.87

0.92/–5.32

–1.00/–3.40

1.92

N(Ph-2T-DCN-Hex)3

517

525

657

1.89

0.94/–5.34

–0.99/–3.41

1.93

N(Ph-2T-DCN-Dodec)3

517

525

657

1.89

0.94/–5.34

–1.00/–3.40

a)Measured

in ODCB solution;

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b)Cast

from chloroform solution;


c)Bandgap

estimated from the onset wavelength (λedge) of the optical absorption: Eg


1.94 opt

= 1240/λedge.



FULL PAPER Figure 2. Tapping mode AFM surface scans (5 × 5 μm2) of films without any post-treatment of a) N(Ph-2T-DCN-Me)3:PC70BM (RMS = 0.59 nm), b) N(Ph-2T-DCN-Et)3:PC70BM(RMS = 0.44 nm), c) N(Ph-2T-DCN-Hex)3:PC70BM (RMS = 0.52 nm), and d) N(Ph-2T-DCN-Dodec)3:PC70BM (RMS = 0.64 nm).

to the solution spectrum is the largest for N(Ph-2T-DCN-Me)3; the absorption peak maximum is red-shifted by 23 nm, from 517 nm in solution to 541 nm in thin film, leading to a more narrow bandgap of 1.74 eV, as shown in Figure 1b. These results indicate that there are strong intermolecular interactions leading to aggregation in the N(Ph-2T-DCN-Me)3 film. It is likely that methyl, being the shortest end group in N(Ph2T-DCN-Me)3, could reduce steric hindrance and eliminate torsional interactions between the DCN groups and bithiophene as the π-bridge and extend the conjugation length of each branch in the molecule. The electrochemical properties of the four TPA-based molecules were investigated using cyclic voltammetry (CV) (see Table 1 and Supporting Information Figure S39–S46). The onset reduction potential (φred), the onset oxidation potential (φox) and the electrochemical bandgap (EgEC) of the molecules are listed in Table 1. From the values of φred and φox of the four TPA-based molecules, the lowest unoccupied molecular orbital (LUMO) and HOMO energy levels of these molecules were also calculated as shown in Table 1, according to the equations of LUMO = –e(φred+ 4.40) (eV) and HOMO = –e(φox + 4.40) (eV).[26] The LUMO and HOMO energy levels of these molecules were all around –3.41 eV and –5.32 eV, respectively. This suggests


that the alkyl chain length has almost no influence on the LUMO and HOMO levels of these four small molecules. 2.3. Morphology and Structure of Small Molecule:Fullerene Thin Films The active layer surface morphology of OSCs was examined using atomic force microscopy (AFM) in tapping mode. Figure 2 shows the AFM topography images of the blend films of N(Ph2T-DCN-Me)3:PC70BM, N(Ph-2T-DCN-Et)3:PC70BM, N(Ph-2TDCN-Hex)3:PC70BM, and N(Ph-2T-DCN-Dodec)3:PC70BM (1:2, wt%) respectively, without any post-treatment. AFM images of N(Ph-2T-DCN-Me)3:PC70BM film show smooth surfaces (root mean square (RMS) roughness of 0.59 nm) with no visible macroscopic phase separation. This suggests good dispersion of both molecules, forming sufficient number of nanoscale aggregated domains and a well interpenetrated network, which is beneficial for efficient charge separation. Compared with the N(Ph-2T-DCN-Me)3:PC70BM film, the surface relief and the domain size seem to slightly grow for the N(Ph-2T-DCNEt)3:PC70BM and N(Ph-2T-DCN-Hex)3:PC70BM films with RMS roughnesses of 0.44 and 0.52 nm, respectively. However,



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www.advenergymat.de Table 2. Photovoltaic properties of small molecules:PC70BM OSCs without post-treatment. Weight ratios

Voc [V]

Jsc [mA cm−2]

FF [%]

PCE [%]

N(Ph-2T-DCN-Me)3:PC70BM

1:1

0.96

7.64

53

3.89


1:1.5

0.96

7.71

54

4.00


1:2

0.98

8.67

56

4.76


1:2.5

0.98

8.26

51

4.13

N(Ph-2T-DCN-Et)3:PC70BM

1:2

0.96

7.86

46

3.47

N(Ph-2T-DCN-Hex)3:PC70BM

1:2

0.98

8.04

44

3.46

N(Ph-2T-DCN-Dodec)3:PC70BM

1:2

1.00

7.00

41

2.87

Active layer

0

a N(Ph-2T-DCN-Me)3 N(Ph-2T-DCN-Et)3

-2

N(Ph-2T-DCN-Hex)3 N(Ph-2T-DCN-Dodec)3

-4 -6 -8

0.0

0.2

0.4 0.6 Voltage (V)

2.4. Photovoltaic Properties of BHJ Devices Here, we first optimized the blending ratios of the N(Ph-2TDCN-Me)3:PC70BM active layer. The corresponding device parameters with different blending ratios are shown in Figure S49 (Supporting Information) and summarized in Table 2. Optimized performances were achieved with a N(Ph2T-DCN-Me)3:PC70BM weight ratio of 1:2, and optimized devices without any post-treatments show an open-circuit voltage (Voc) of 0.98 V, a short circuit current density (Jsc) of 8.67 mA cm−2, and a fill factor (FF) of 56%, giving a PCE of 4.76%. Decreasing or increasing the PC70BM content of blends resulted in a decrease of the Jsc and PCE values of the PSCs, as shown in Table 2. The performance decrease could arise from donor/acceptor ratios resulting in unbalanced hole-electron transport. In order to more generally understand the impact of the alkyl chain length on the structure–property relationships, we fabricated BHJ solar cells under identical processing conditions for all four star-shaped small molecules, keeping the small molecule:PC70BM ratio (1:2), the thickness (ca. 90 nm), and all other processing parameters identical. The current–voltage characteristics and the relative difference of the longer alkyl chain molecules compared to N(Ph-2T-DCN-Me)3 are shown in Figure 3a,b, with the representative performance parameters listed in Table 2. In the following, we individually analyze and discuss the impact of alkyl chains on Voc, Jsc, and FF of related Normalized photovoltaic parameters

N(Ph-2T-DCN-Dodec)3:PC70BM film (Figure 2d) shows relatively coarse surface with the RMS roughness of 0.64 nm, and without noticeable aggregated domains at the resolution of the AFM. Those results may be attributed to the additional intermolecular forces from the longer dodecyl alkyl side chains, revealed by WAXS studies of the pure material (see Supporting Information, Figure S38, curves 3–5) and its poor film-forming characteristics. Although AFM provides insight into the top surface morphology, it is not necessarily representative of the bulk morphology of the thin films.[27] To gain insight into the structural differences such as crystallite size, intermolecular distance, and crystallite orientation in blend films, we further conducted X-ray reflectivity and grazing incidence X-ray scattering (GIWAXS) (Figure S47,S48, Supporting Information). However, both methods suggested that these blends are predominantly amorphous. X-ray reflectivity only resolved the positions of minima (Figure S47, Supporting Information) corresponding to a film thickness of about 500 Å. Therefore, substantial roughness of their surface does not allow unambiguous analysis of the distribution of the electron density along the substrate director. In addition, grazing incidence diffraction patterns reveal a strong maxima at s = 1.346 Å−1 and s = 1.957 Å−1 in both blend films corresponding to scattering from liquidlike phase of PC70BM,[28] as shown in Figure S48 (Supporting Information).

Current density (mA/cm*cm)

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0.8

1.0

1.0

b

0.9

0.8

0.7

0.6

Voc (0.98 V) -2 Jsc (8.67 mAcm ) FF (56 %) PCE(4.76 %)

Methyl

Ethyl

Hexyl

Dodecyl

Alkyl side chains

Figure 3. a) Current density–voltage (J–V) curves and b) relative different compared to N(Ph-2T-DCN-Me)3 parameters of solar cells based on the four small molecules, under illumination of AM 1.5 (100 mA cm−2).

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BHJ devices based on this series of four star-shaped small molecules.

2.4.2. Short Circuit Current ( Jsc) A major impact on the efficiency stems from changes in Jsc (as shown in Figure 3b). The EQE spectra of the devices based on the various blends with the same weight ratio (1:2) of donor to acceptor, which are consistent with the absorption spectra of related blends and all exhibit comparable photon response extending from 330 to 700 nm, are shown in Figure S50 (Supporting Information) and Figure 4. The Jsc calculated from the EQE are 8.54 mA cm−2 for N(Ph-2T-DCN-Me)3, 7.39 mA cm−2 for N(Ph-2T-DCN-Et)3, 7.61 mA cm−2 for N(Ph-2T-DCNHex)3, and 6.65 mA cm−2 for N(Ph-2T-DCN-Dodec)3, which are consistent with the values of Jsc measured under simulated 60 50

EQE(%)

40 30 20

N(Ph-2T-DCN-Me)3

10

N(Ph-2T-DCN-Hex)3

N(Ph-2T-DCN-Et)3 N(Ph-2T-DCN-Dodec)3

0 400

500

600

700

Wavelength (nm) Figure 4. EQE curves of the best OSCs based on small molecules:PC70BM blends with the same weight ratio of 1:2.


-2

Voc is significantly influenced by the difference between the LUMO level of the acceptor and the HOMO level of the donor, and depressed HOMOs of the donor materials are expected to lead to higher Voc values.[29] Normally, strong acceptor units and electron-withdrawing heteroatoms substituents (e.g., F, O) were introduced to reduce the small molecule HOMO energy level for an increase in Voc.[30–32] In addition, the Voc values for devices could be significantly influenced by the alkyl chain. For example, Chen and co-workers synthesized two small molecules with octyl and 2-ethylhexyl as alkyl chains. In terms of octyl substitution, a 2-ethylhexyl-based molecule leads to a 0.07 V increase in Voc when compared with that of the corresponding octyl-based molecule-based device.[15] However, the alkyl chain length does not significantly impact the energy levels of these four small molecules in this study. Thus, these molecule-based device properties exhibited similar Voc values. Interestingly, N(Ph-2T-DCN-Dodec)3 showed a slightly increased Voc of up to 1.0 V. These small differences may be explained by the longer dodecyl chains leading to a weakening of the intermolecular interactions between the donor and acceptor moieties.[33]

Mobility [cm /Vs]

1E-3

2.4.1. Open Circuit Voltage (Voc)

1E-4

1E-5

1E-6

hole only mobility electron only mobility

t)3 e)3 x)3 ec)3 CN-M -2T-DCN-E T-DCN-He -Dod -2T-D -DCN -2 T h 2 P N(Ph ( h N(Ph N N(P Figure 5. Hole-only mobility and electron-only mobility of binary blends with the four TPA-based molecules as the donor and PC70BM as acceptor.

AM 1.5. The highest Jsc from the N(Ph-2T-DCN-Me)3 with methyl groups can be partially ascribed to a broader spectral sensitivity (as shown in Figure 1b and Supporting Information, Figure S50). In addition, and consistent with the AFM data reported above, N(Ph-2T-DCN-Me)3:PC70BM films may offer better-expressed nanoscale aggregated domains well interconnected to each other as compared to the other three molecules. Such nanoscale domains are expected to indemnify charge separation and/or transport and, consequently, to enhance the collection of photocurrent in the electrodes. In order to further understand the relationship between the charge carrier transport properties and structure of these four small molecule:PC70BM (1:2, wt%) blends, and the current density of these blend based devices, the charge carrier mobilities were determined from space charge limited current (SCLC) measurements on representative thin film devices for a range of thicknesses, as shown in Figure 5 and Table 3. The structures of hole only and electron only devices are ITO/PEDOT:PSS/ active layer/PEDOT:PSS/Ag and ITO/AZO/active layer/Ca/ Ag, respectively. We calibrated the hole and electron mobility by fitting the current–voltage curves (Figure S51, Supporting Information).[14] The hole and electron mobility obtained for the N(Ph-2T-DCN-Me)3:PC70BM (1:2, wt%) blend films are 4.65 × 10−4 and 1.41 × 10−3 cm2 V−1 s−1, respectively. The hole and electron mobility for the other three molecules with ethyl-, hexyl-, and dodecyl-based devices gradually decreased in both cases relative to the N(Ph-2T-DCN-Me)3:PC70BM based devices, as shown in Figure 5. In combination with the broader spectral sensitivity, the higher hole and electron mobilities of the N(Ph2T-DCN-Me)3 based blends are in agreement with the trend observed for the Jsc. The lowest Jsc is observed for the N(Ph2T-DCN-Dodec)3 based device, which also had the lowest hole and electron mobility. While the electron only mobility of N(Ph2T-DCN-Et)3 and N(Ph-2T-DCN-Hex)3 are similar, the hole mobility of N(Ph-2T-DCN-Hex)3 is already significantly lower. Interestingly, the Jsc of N(Ph-2T-DCN-Et)3 based device shows a comparable value to the N(Ph-2T-DCN-Hex)3 based device. This suggests that carrier extraction is not drastically limiting for the device performance, but recombination of the carriers



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www.advenergymat.de Table 3. Hole and electron mobilities determined from the SCLC measurements. Donor:PC70BM (1:2)

Thickness [nm]

Hole mobility (μh) [cm2 V−1 s−1]

Thickness [nm]

Electron mobility (μe) [cm2 V−1 s−1]

μe/μh

N(Ph-2T-DCN-Me)3

120 ± 5

4.65 × 10−4

105 ± 5

1.41 × 10−3

3.0

N(Ph-2T-DCN-Et)3

100 ± 5

4.23 × 10−4

80 ± 5

1.09 × 10−3

2.6

N(Ph-2T-DCN-Hex)3

125 ± 5

7.54 × 10

−5

68 ± 5

−4

7.89 × 10

10.5

N(Ph-2T-DCN-Dodec)3

117 ± 5

1.94 × 10−6

73 ± 5

6.45 × 10−4

333

is. Therefore, it is necessary to gain insights into the observed difference in the device performance using other characterization methods. We further investigated the recombination dynamics respectively the charge carrier lifetime of all four compounds at different light intensities (from 0.1 up to 1 sun) by transient photovoltage (TPV), as shown in Figure 6. Fitting the data was done by a pseudo-first-order rate equation of the form:[14,34]

dV dn n ∝ = − keff = − dt dt Jn Where ΔV is the photovoltage, t is the time, Δn is the change in the density of photogenerated carriers density due to the perturbation pulse, keff is the pseudo-first order rate constant, and τΔn is the corresponding carrier lifetime. τΔn was determined from photovoltage transients recorded at different light biases ranging from 0.1–1 suns. Details about the measurement data used to study the recombination kinetics of devices are exhibited in the Supporting Information (Figure S52–S55). The TPV data exhibit the highest lifetimes for the N(Ph-2T-DCNMe)3:PC70BM devices compared to the other three devices with N(Ph-2T-DCN-Et)3, N(Ph-2T-DCN-Hex)3, and N(Ph-2T-DCNDodec)3 as donor materials. Interestingly, Figure 6 shows that N(Ph-2T-DCN-Et)3:PC70BM and N(Ph-2T-DCN-Hex)3:PC70BM devices exhibited comparable recombination dynamics at different charge densities, which further illustrates the similar Jsc

N(Ph-2T-DCN-Me)3 N(Ph-2T-DCN-Et)3 N(Ph-2T-DCN-Hex)3 N(Ph-2T-DCN-Dodec)3

1E-5 τ [s]

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1E-6 0.0

0.2

0.4 0.6 0.8 light intensity in suns

1.0

Figure 6. Small perturbation charge carrier lifetime measured by transient photovoltage (TPV) technique for the four small-molecule-based devices.

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values obtained for both devices. In particular, the lifetime for the N(Ph-2T-DCN-Dodec)3 based device is significantly lower than those for the other three, which is ascribed to the less favorable morphology, and thus accounts for the lowest Jsc for the N(Ph-2T-DCN-Dodec)3 based device. 2.4.3. Fill Factor (FF) A slight modification of the alkyl chain also varied the FF of devices remarkably due to the different morphological behavior in the solid state, which is crucial for charge transport and exciton extraction.[16] The relationship between charge transport and FF in small molecule:fullerene systems is well established.[14,16] Compared with polymer:fullerene systems,[35,36] this is the same relation as when measuring the hole and electron mobilities:[37] if the hole and electron carrier mobilities are too low or heavily unbalanced, charges cannot be swept out efficiently before the recombination, which results in low FFs and quantum efficiencies. As mentioned above, the electron mobility, μe, of N(Ph-2T-DCN-Me)3 is 1.41 × 10−3 cm2 V−1 s−1 and the hole mobility, μh, is 4.65 × 10−4 cm2 V−1 s−1, a factor of 3.0 lower than the electron mobility. Although the hole and electron mobilities of N(Ph-2T-DCN-Et)3 based devices are slightly less than these of N(Ph-2T-DCN-Me)3 based devices, the μe/μh ratio is only 2.6. Conversely, N(Ph-2T-DCN-Hex)3 and N(Ph-2TDCN-Dodec)3 based devices reveal a significantly lower μh of 7.54 × 10−5 and 1.94 × 10−6 cm2 V−1 s−1 as well as the high μe/μh ratios of 10.5 and 333, respectively. These results suggest that N(Ph-2T-DCN-Me)3 and N(Ph-2T-DCN-Et)3 based solar cells have a relatively higher FF compared to the other two devices, as shown in Table 2. In addition, although the μe decreased slightly with the increase of the length of the alkyl chain, the high and similar μe observed in each system is consistent with the expectation that the μe in blend films should be comparable to the electron mobility of pristine fullerene films.[37–39] However, a lack of convincing result is that the almost one order of magnitude lower hole mobility measured in the N(Ph-2T-DCNHex)3 diode compared to the N(Ph-2T-DCN-Et)3 one, which suggests that N(Ph-2T-DCN-Hex)3 based solar cells may be transport limited, but the FF only decreased slightly from 0.46 to 0.44. Thus, further study of the recombination limitation is necessary because charge carrier extraction (due to trapping or bimolecular recombination) could also significantly influence the FF observed in the solar cells.[37,40] Therefore, in order to gain additional insights into the observed differences in FF and efficiency as the length of alkyl chains substituents are varied, we first calculated the photocurrent (Jph) by subtracting the current density in the dark from



www.advenergymat.de www.MaterialsViews.com 1.0

a

Charge Collection Probability

Jph Density (mA/cm2)

10

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12

8 6

N(Ph-2T-DCN-Me)3

4

N(Ph-2T-DCN-Et)3 N(Ph-2T-DCN-Hex)3

2

N(Ph-2T-DCN-Dodec)3 0 0.0

0.5

1.0

1.5

2.0

2.5

3.0

b 0.8

0.6

0.4

N(Ph-2T-DCN-Me)3 N(Ph-2T-DCN-Et)3

0.2


0.0 -2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

Voltage (V)

Vo-V (V)

Figure 7. a) Photocurrent density vs. effective voltage, Vo is the compensation voltage and b) charge collection probability vs. applied voltage of optimized BHJ solar cells under 1 sun.

the current density under illumination (Figure S56, Supporting Information), and then determined the compensation voltage Vo at which Jph = 0.[18] Since recombination losses were dependent on the internal electric field or applied voltage,[18,41] we calculated the charge collection probability (Pc(V)) according to PC (V ) = −

J ph (V ) sat J ph

Figure 7a plots Jph against the effective voltages (given by Vo – V). For large reverse voltages (Vo – V > 1 V), the photocurrent becomes saturated and almost all free carriers are extracted by the applied field and collected of the electrodes, leading to the sat [41] saturated photocurrent that is field-independent ( J ph ). Here, sat ( we assume a saturated photocurrent J ph = J ph Vo − V = 3 V) , and estimate the Pc(V) curves of the studied devices, as shown in Figure 7b. For small applied reverse voltages (V > –1 V), the Pc(V) varies significantly due to differences in field-dependent recombination losses. Under this weak applied fields where the FF is determined, the device based on N(Ph-2T-DCN-Me)3 achieved the highest charge collection probability, while its counterpart of N(Ph-2T-DCN-Dodec)3 achieved the lowest (for example, V = 0.5 V). The two N(Ph-2T-DCN-Et)3 and N(Ph2T-DCN-Hex)3 based blends show the comparable charge collection probability, which is in-between the blends consisting of N(Ph-2T-DCN-Me)3 and N(Ph-2T-DCN-Dodec)3. This further explains why N(Ph-2T-DCN-Et)3 and N(Ph-2T-DCN-Hex)3 based devices exhibited comparable FF values. Comparing the other three blends, the optimal morphology and improved mobilities in the N(Ph-2T-DCN-Me)3 blend retard the recombination of free charge carriers during charge transport, leading to an improved charge collection probability and hence the highest FF of 56%. Combined with the broader absorption, a good interpenetrating network and highest charge carrier lifetime, a high overall photovoltaic efficiency exceeding 4.76% was received for this device.

3. Conclusions In summary, we have synthesized four novel small molecules with D-π-A structure and have demonstrated the first attempt Adv. Energy Mater. 2014, 4, 1301234

to study the structure–property relationships with various lengths of alkyl end groups (methyl, ethyl, hexyl, and dodecyl) on the star-shaped TPA-based small molecules. All the molecules exhibit good thermal stability, similar absorption spectra in solution, and a relatively low and similar HOMO levels. However, the N(Ph-2T-DCN-Me)3, which has methyl as the end groups, shows relatively broaden absorption in the film and higher hole and electron mobilities as well as longer carrier lifetime in devices, compared with the other three molecules. The PCE of the solution-processed OSCs based on N(Ph-2T-DCNMe)3:PC70BM (1:2, wt%), without any post-treatment, reached 4.76% with a Voc of 0.98 V, a Jsc of 8.67 mA cm−2, and a FF of 56%, under the illumination of AM1.5G, 100 mA cm−2, indicating that introduction of methyl end groups instead of the relatively long alkyl chain may reduce steric hindrance and torsional interactions of the molecule and thereby enhance the intermolecular interactions, charge separation and transportation, charge carrier lifetime and consequently improving the photovoltaic performances. This preliminary work demonstrates that using the principles of alkyl chain engineering on star-shaped molecules has great significance for designing high-performance small-molecule OSCs.

Supporting Information Supporting Information is available from the Wiley Online Library or from the author.

Acknowledgements The authors gratefully acknowledge the support of the Cluster of Excellence ‘‘Engineering of Advanced Materials’’ at the University of Erlangen-Nuremberg, which is funded by the German Research Foundation (DFG) within the framework of its ‘‘Excellence Initiative’’. This work was partially funded by the Sonderforschungsbereich 953 “Synthetic Carbon Allotropes”, the China Scholarship Council (CSC), the Ministry of Education and Science of the Russian Federation (11. G34.31.0055), the Program of President of Russian Federation for Support of Young Scientists (grant MK-6716.2013.3) and by the Russian Foundation for Basic Research (grant No12–03–31225). The authors



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www.MaterialsViews.com also thank the Solar Technologies go Hybrid (SolTech) and the beamline P09 at Petra III DESY synchrotron source for financial support. Received: August 15, 2013 Revised: September 15, 2013 Published online: October 22, 2013

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Supporting Information for Adv. Energy Mater., DOI: 10.1002/aenm.201301234

Alkyl Chain Engineering of Solution-Processable Star-Shaped Molecules for High-Performance Organic Solar Cells Jie Min,* Yuriy N. Luponosov, Andreas Gerl, Marina S. Polinskaya, Svetlana M. Peregudova, Petr V. Dmitryakov, Artem V. Bakirov, Maxim A. Shcherbina, Sergei N. Chvalun, Souren Grigorian, Nina Kaush-Busies, Sergei A. Ponomarenko, Tayebeh Ameri, and Christoph J. Brabec

Alkyl Chain Engineering on Solution-Processable Star-Shaped Molecules toward High-Performance Organic Solar Cells

Jie Min*1，Yuriy N, Luponosov3, Andreas Gerl1, Marina S. Polinskaya3, SvetlanaM. Peregudova5, Petr V. Dmitryakov3, Artem V. Bakirov3, Maxim А. Shcherbina3, Sergei N. Chvalun3, Souren Grigorian6, Nina Kaush-Busies7, Sergei A. Ponomarenko3,4, TayebehAmeri1, Christoph J. Brabec1,2

1

Institute of Materials for Electronics and Energy Technology (I-MEET),Friedrich-Alexander-University Erlangen-Nuremberg, Martensstraße 7, 91058 Erlangen, Germany 2 Bavarian Center for Applied Energy Research (ZAE Bayern), Haberstraße 2a, 91058 Erlangen, Germany 3 Enikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences, Profsoyuznayast. 70, Moscow 117393, Russia 4 Chemistry Department, Moscow State University, Leninskie Gory 1-3, Moscow 119991, Russia 5 Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova St. 28, Moscow, 119991, Russia 6 Institute of Physics, University of Siegen, Emmy-Noether-Campus, Walter-Flex-Str. 3, D-57068 Siegen, Germany 7 Heraeus Precious Metals GmbH & Co. KG, Conductive Polymers Division (Clevios), Chempark Leverkusen Build. B202, D-51368 Leverkusen, Germany

E-mail: [email protected] (J. Min)

1. Experimental Section 1.1 General. GPC analysis was performed by means of a Shimadzu LC10AVP series chromatograph (Japan) equipped with an RID-10AVPrefractometer and SPD-M10AVP diode matrix as detectors and a Phenomenex column (USA) with a size of 7.8×300 mm2 filled with the Phenogel sorbent with a pour size of 500 Å; THF was used as the eluent. Glassware was

dried in a drybox at 150 °C for 2 h, assembled while hot, and cooled in a stream of argon. For thin layer chromatography, “Sorbfil” (Russia) plates were used. In the case of column chromatography, silica gel 60 (“Merck”)was taken. 1

Н-NMR spectra were recorded at a “Bruker WP-250 SY “spectrometer, working at a

frequency of 250.13 MHz and utilising CDCl3 signal (7.25 ppm) as the internal standard. 13C spectra were recorded using a “Bruker Avance II 300” spectrometer at 75 MHz. In the case of 1НNMR spectroscopy, the compounds to be analysed were taken in the form of 1% solutions in CDCl3. In the case of

13

CNMR spectroscopy, the

compounds to be analysed were taken in the form of 5% solutions in CDCl3. The spectra were then processed on the computer using the ACD Labs software. High resolution mass spectra (HR MS) were measured on a Bruker micro TOF II instrument using electrospray ionization (ESI). The measurements were done in a positive ion mode (interface capillary voltage – 4500 V) or in a negative ion mode (3200 V); mass range from m/z 50 to m/z 3000 Da; external or internal calibration was done with Electrospray Calibrant Solution (Fluka). A syringe injection was used for solutions in acetonitrile, methanol, or water (flow rate 3 L/min). Nitrogen was applied as a dry gas; interface temperature was set at 180 °C. Elemental analysis of C, H, N elements was carried out using CHN automatic analyzer CE 1106 (Italy). The settling titration using BaCl2 was applied to analyze sulphur. Experimental error is 0.30-0.50%. The Knövenagel condensation was carried out in the microwave “Discovery”, (CEM corporation, USA), using a standard method with the open vessel option, 50

watts. Thermogravimetric analysis was carried out in dynamic mode in 30 ÷ 900°C interval using Mettler Toledo TG50 system equipped with M3 microbalance allowing measuring the weight of samples in 0 ÷ 150 mg range with 1 g precision. Heating/cooling rate was chosen to be 10°C/min. Every compound was studied twice: in air and in nitrogen flow of 200 mL/min. DSC scans were obtained with Mettler Toledo DSC30 system with 20°C/min heating/cooling rate in temperature range of +20 ÷ 250°C for all compounds but N(Ph-2T-DCN-Dodec)3 having substantially low glass transition temperature for which a range of -20 ÷ 250°C was chosen. Nitrogen flow of 50 mL/min was used. X-Ray diffraction patterns in small and wide angle scattering regions were obtained using S3-Micropix system (Hecuscompany), CuK-radiation,  = 1.5406 Å with XenocsGenix source (working voltage and current were 50 kV and 1 mA respectively). Pilatus 100K detector was employed, as well as linear PSD 50M gas detector (Ar/Me mixture at 8·105 Pa). Collimation system Fox 3D with Kratky collimation slits of 0.1 mm and 0.2 mm width was used, allowing the stable measurements in wave vector interval from s = 0.003 Å-1 to s = 1.9 Å-1 where s = 4sin/, 2 is scattering angle. To get rid of the scattering of X-Rays on air molecules, Goebbel mirrors and scattering path are vacuumed at pressures 2.6 ÷ 5.0 Pa. Exposure times were varied from 600 – 5000 s. Temperature behavior of samples was studied using Peltier and Joule attachments at low (-5˚С - 120˚С) at Joule and high (23˚С - 300˚С) temperatures correspondingly. Transmission X-Ray diffraction patterns at wide angles were also recorded at Bruker D8 Advance powder diffractometer (CuK-radiation,  = 1.5406 Å, Vantec 2D detector). Accelrys Materials Studio® program set was employed for molecular modeling of compounds studied. We used two sets of potentials, which allow taking into account non-covalent interactions of molecules: COMPASS (Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies) and UFF (Universal Force Field). The COMPASS set is suitable for modeling of isolated molecules and

condensed phases of mainly organic, polymeric and of some inorganic compounds[1,2,3], it also allows to parametrize partial charges and valencyab initio with subsequent system optimization. To prove the results of modelling, we applied UFF potentials, as it does not have any limitation on the chemistry of compounds involved [4-6]. Absorption profiles were recorded with a Perkin Elmer Lambda-35 absorption spectrometer from 350 to 1100. Electrochemical properties were studied by cyclic voltammetry (CVA). The measurements were carried out in the 1, 2-dichlorobenzene: acetonitrile (4:1) mixture of solvents using 0.1 M Bu 4NPF6 as supporting electrolyte. The glassy carbon electrode was used as a work electrode. Potentials were measured relative to a saturated calomel electrode.

1.2 Materials. n-Butyl

lithium

(1.6

M

solution

in

hexane),

magnesium,isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane(IPTMDOB), tetrakis(triphenylphosphine)palladium(0)Pd(PPh3)4, p-toluenesulfonic acid (p-TosH), tris(4-bromophenyl)amine, malononiltile, heptanoyl chloride, acetyl chloride, tridecanoyl chloride were obtained from Sigma–Aldrich Co. and usedwithout further. THF, benzene, pyridine and ethylene glycol were dried and puriﬁed according to the known techniques and then used as solvents. 5-bromo-2,2’-bithiophenewas obtained from Heraeus Precious Metals GmbH & Co.Li2MnCl4 was obtained as described in Ref. [7]. Synthesis of compounds 1b-5b and N(Ph-2T-DCN)Et3was described previously[8]. Synthesis

1-(2,2'-bithien-5-yl)ethanone (1a). A solution of 5-bromo-2,2'-bithiophene (18g, 73.4 mmol) in 170mL of THF was added dropwise to a suspension of magnesium (1.8 g, 75.0mmol) in 10 mL of THF. The Grignard reagent was refluxed for 2 h, then cooled to room temperature and added dropwise to solution of acetyl chloride (5.76 g, 73.4 mmol) and freshly prepared Li2MnCl4 (1.84 mmol) in 50 mL of THF at 0 °C. After addition of the Grignard reagent the cooling bath was removed and stirring was continued for 1 hour. After completion of the reaction it was poured into 400 mL of distilled water and extracted three times with freshly distilled diethyl ether. The solvent was evaporated in vacuum and the residue was dried at 1 Torr to give the crude product in 91% reaction yield (according to 1H NMR). It was purified by distillation in vacuum (0.2 mBar, 133 °C) to give pure compound 1a (11 g, 72 %) as a white solid. 1H NMR (250 MHz, CDCl3, , ppm): 2.54 (s, 3H), 7.05 (dd, 1H, J1 = 3.7, J2 = 1.1 Hz), 7.15 (d, 1H, J = 4.3 Hz), 7.28-7.33 (overlapping peaks, 2H), 7.58 (d, 1H, J = 4.3 Hz).

13

C NMR (75 MHz,

CDCl3): δ [ppm] 26.49, 124.10, 125.60, 126.46, 128.21, 133.31, 136.29, 142.35, 145.74, 190.39. Calcd (%) for C10H8OS2: C, 57.66; H, 3.87; S, 30.79. Found: C, 57.41; H, 3.99; S, 30.83. HRESIMS: found m/z 209.0094; calculated for [M +H]+ 209.0100. 2-(2,2'-bithien-5-yl)-2-methyl-1,3-dioxolane (2a).Compound 1a(8.73 g, 41.9 mmol) was dissolved in dry benzene (170 mL). After complete dissolution p-TosH (1.59 g, 8.4 mmol) and ethylene glycol (94 mL, 1.68 mol) were added. Then the mixture was stirred at reflux for 17 hours using a Dean-Starck water separator. After that the saturated aqueous sodium bicarbonate solution was added and the mixture was extracted 3 times with toluene (300 mL). The combined organic phases were dried over sodium sulfate and filtered. The solvent was evaporated in vacuum and the residue was dried at 1 Torr to give 9.57 g of crude product in 82% reaction yield (according to 1H NMR). This crude product was purified by column chromatography on silica gel (eluent toluene and then mixture toluene:ethyl acetate (10:1)) to give pure product (5.71 g, 54%) as a colorless liquid. 1H NMR (250 MHz, CDCl3, , ppm): 1.78 (s, 3H), 3.97–4.07 (overlapping peaks, 4H), 6.93 (d, 1H, J = 3.7 Hz), 6.97 (d, 1H, J = 3.7), 7.01 (d, 1H, J = 3.7 Hz), 7.12 (d, 1H, J = 3.7 Hz), 7.18 (d, 1H, J = 4.3 Hz). Calcd (%) for C12H12O2S2: C, 57.12; H, 4.79; S, 25.41. Found: C, 57.01; H, 4.85; S, 25.32.

2-[5'-(2-methyl-1,3-dioxolan-2-yl)-2,2'-bithien-5-yl]-4,4,5,5-tetramethyl-1,3,2 -dioxaborolane (3a). 2.5 M solution of butyllithium (9.1 mL, 22.6 mmol) in hexane was added dropwise to a solution of compound 2a (5.71 g, 22.6 mmol) in 250 mL of THF -78 ºC. After the reaction mixture was stirred for 60 min at -78 ºC, IPTMDOB (4.62 mL, 22.6 mmol) was added in one portion. The reaction mixture was stirred for 1 h at –78 ºC, then the cooling bath was removed, and the stirring was continued for 1 h. After completion of the reaction, 400 mL of freshly distilled diethyl ether and 200 mL of distilled water and 22 mL of 1 M HCl were added to the reaction mixture. The organic phase was separated, washed with water, and dried over sodium sulfate and filtered. The solvent was evaporated to give 9.27 g (90%) of the pure product (purity was 98% according to 1H NMR) as a blue solid. The product was used in the subsequent synthesis without further purification. 1H NMR (250 MHz, CDCl3, , ppm): 1.34 (s, 12H), 1.78 (s, 3H), 3.97–4.05 (overlapping peaks, 4H), 6.93 (d, 1H, J = 3.7 Hz), 7.06 (d, 1H, J = 3.7 Hz),7.17 (d, 1H, J = 3.7Hz), 7.49 (d, 1H, J = 3.7Hz). 13C NMR (75 MHz, CDCl3): δ [ppm] 24.72, 27.43, 64.96, 84.15, 107.00, 124.06, 124.83, 124.89, 136.79, 137.90, 144.02, 146.91. Calcd (%) for C18H23BO4S2: C, 57.15; H, 6.13; S, 16.95. Found: C, 57.18; H, 6.18; S, 16.79. HRESIMS: found m/z 379.1195; calculated for [M]+ 379.1173. tris{4-[5'-(2-methyl-1,3-dioxolan-2-yl)-2,2'-bithien-5-yl]phenyl}amine (4a). In an inert atmosphere, degassed solutions of tris(4-bromophenyl)amine (2,04 g, 4,2 mmol) and compound 3a (5,57 g, 14,7 mmol) in toluene/ethanol mixture (100/10 mL) and 2M solution of aq. Na2CO3 (6 mL) were added to Pd(PPh3)4 (245 mg, 0.2 mmol). The reaction mixture was stirred under reflux for 22 h, and then it was cooled to room temperature and poured into 150 mL of water and 250 mL of toluene. The organic phase was separated, washed with water, dried over sodium sulfate and filtered. The solvent was evaporated in vacuum and the residue was dried at 1 Torr. The product was purified by column chromatography on silica gel (eluent toluene: ethyl acetate 10:1) to give pure compound 4a (1,71 g, 40%) as yellow solid. 1H NMR (250 MHz, DMSO-d6): δ [ppm] 1.68 (s, 9H), 3.87–4.05 (overlapping peaks, 12H), 7.02 (d, 3H, J = 3.7 Hz), 7.08 (d, 6H, J = 8.5 Hz), 7.17 (d, 3H, J = 3.7 Hz), 7.28 (d, 3H, J = 3.7 Hz), 7.41 (d, 3H, J =

4.3 Hz), 7.62 (d, 6H, J = 8.5 Hz). 13C NMR (75 MHz, CDCl3): δ [ppm] 27.41, 64.97, 107.02, 123.08, 123.11, 124.37, 124.52, 124.85, 126.48, 128.88, 135.98, 137.02, 142.72, 146.08, 146.37. Calcd (%) for C54H45NO6S6: C, 65.10; H, 4.55; N, 1.41; S, 19.31. Found: C, 64.87; H, 4.63; N, 1.35; S, 19.12. HRESIMS: found m/z 995.1532; calculated for [M]+ 995.1566. 1,1',1''-[nitrilotris(4,1-phenylene-2,2'-bithiene-5',5-diyl)]triethanone (5a). 1M HCl (4.83 mL) was added to a solution of compound 4 (1.604 g, 1.6 mmol) in THF (200 mL) and then the reaction mixture was stirred for 3 hours at reflux at boiling temperature. During the reaction the product was gradually formed orange precipitate. After completion of the reaction the organic phase was separated using diethyl ether, washed with water and filtered off to give pure compound 5a (1.3 g, 94%) as orange crystals. 1

H NMR (250 MHz, DMSO-d6): δ [ppm] 2.50 (9H, s), 7.10 (d, 6H, J = 8.5 Hz), 7.30

(3H, d, J = 3.7 Hz), 7.35–7.44 (6H, overlapped peaks), 7.55 (d, 6H, J = 8.5 Hz ), 7.76 (d, 3H, J = 4.3 Hz). Calcd (%) for C48H33NO3S6: C, 66.71; H, 3.85; N, 1.62; S, 22.26. Found: C, 66.30; H, 3.56; N, 1.55; S, 21.88. HRESIMS: found m/z 863.078; calculated for [M]+ 863.0775. tris{4-[5'-(1,1-dicyanoprop-1-en-2-yl)-2,2’-bithien-5-yl]phenyl}amine– N(Ph-2T-DCN-Me)3.Compound 5a (1.15 g, 1.3 mmol), malononitrile (0.8 g, 12.0 mmol) and dry pyridine (25 mL) were placed in a reaction vessel and stirred under argon atmosphere for 8 hours at 105 ºС using the microwave heating. After completeness of the reaction the pyridine was evaporated in vacuum and the residue was dried at 1 Torr. This crude product was purified by column chromatography on silica gel (eluent dichloromethane). Further purification included precipitation of the product from its THF solution with toluene and hexane to give pure product as a black solid (1.52 g, 60%). 1H NMR (250 MHz, DMSO-d6, Me4Si): δ [ppm] 2.67 (9H, s), 7.10 (d, 6H, J = 8.5 Hz), 7.45 (d, 3H, J = 4.3 Hz), 7.51 (d, 3H, J = 4.3 Hz), 7.54 (d, 3H, J = 3.7 Hz), 7.60 (d, 6H, J = 8.5 Hz), 8.04 (d, 3H, J = 4.3 Hz). 13C NMR (75 MHz, CDCl3): δ [ppm] 22.88, 113.69, 114.28, 123.82, 124.57, 126.93, 127.55, 128.62, 133.83, 134.96, 135.90, 146.36, 146.74, 146.96, 160.70. Calcd (%) for C57H33N7S6: C, 67.90; H, 3.30; N, 9.72; S, 19.08. Found: C, 67.24; H, 3.39; N, 9.45; S, 18.76. HRESIMS: found m/z

1007.1088; calculated for [M]+ 1007.1116.

1-(2,2'-bithien-5-yl)heptan-1-one (1c). 1c was obtained as described for compound 1a using 5-bromo-2,2'-bithiophene (10.5 g, 42.8 mmol), magnesium (1.04 g, 43.7mmol), heptanoyl chloride (6.34 g, 34 mmol) and freshly prepared Li2MnCl4 (1.07 mmol) to give the crude product in 98% reaction yield (according to 1H NMR). It was purified by a column chromatography on silica gel (eluent toluene – hexane 1:1) to give pure product (10.70 g, 94 %) as a white solid. 1H NMR (250 MHz, CDCl3, , ppm): 0.88 (t, 3H, J = 6.7 Hz), 1.20 – 1.45 (overlapping peaks, 6H), 1.73 (m, 2H, M = 5, J = 7.3 Hz), 2.85 (t, 2H, J = 7.3 Hz), 7.05 (dd, 1H, J1 = 3.7, J2 = 1.1 Hz), 7.15 (d, 1H, J = 4.3 Hz), 7.28-7.33 (overlapping peaks, 2H), 7.58 (d, 1H, J = 4.3 Hz).13C NMR (125 MHz, CDCl3): δ [ppm] 14.03, 22.48, 24.85, 28.99, 31.58, 39.02, 124.06, 125.48, 126.33, 128.18, 132.48, 136.38, 142.32, 145.24, 193.27. Calcd (%) for C15H18OS2: C, 64.71; H, 6.52; S, 23.03. Found: C, 64.89; H, 6.61; S, 22.79. 2-(2,2'-bithien-5-yl)-2-hexyl-1,3-dioxolane (2c). 2c was obtained as described for compound 2a using compound 1c (10.0 g, 35.9 mmol), p-TosH (1.37 g, 7.2 mmol) and ethylene glycol (80 mL, 89 g, 1.44 mol) to give the crude product in 85% reaction yield (according to 1H NMR). It was purified by a column chromatography on silica gel (eluent toluene/hexane, 1:1) to give pure product (9.15 g, 79.2%) as a colorless liquid. 1

H NMR (250 MHz, CDCl3, , ppm): 0.87 (t, 3H, J = 6.7 Hz), 1.20 – 1.48 (overlapping

peaks, 6H), 1.40 (m, 2H, M = 5, J = 7.3 Hz), 1.99 (t, 2H, J = 7.3 Hz), 3.93–4.08 (overlapping peaks, 4H), 6.88 (d, 1H, J = 3.7 Hz), 6.97 (dd, 1H, J1 = 3.7, J2 = 1.2 Hz), 7.01 (d, 1H, J = 3.7 Hz), 7.12 (d, 1H, J = 3.7 Hz), 7.18 (d, 1H, J = 4.3 Hz). 13C NMR (125 MHz, CDCl3): δ [ppm] 14.06, 22.55, 23.68, 29.25, 31.71, 40.55, 64.97, 108.98, 123.34, 123.52, 124.28, 125.00, 127.75, 136.86, 137.38, 145.71. Calcd (%) for C17H22O2S2: C, 63.32; H, 6.88; S, 19.89. Found: C, 63.55; H, 6.94; S, 19.75. 2-[5'-(2-hexyl-1,3-dioxolan-2-yl)-2,2'-bithien-5-yl]-4,4,5,5-tetramethyl-1,3,2-dioxa borolane (3c). 3c was obtained as described for compound 3a using compound 2c(8.10 g, 25.1 mmol), 1.6 M solution of butyllthium (15.70 mL, 25.1 mmol) in hexane, IPTMDOB (5.124 mL, 25.1 mmol) to give pure compound 3c (11.26 g, 100%) as

green-blue crystals. The product was used in the subsequent synthesis without further purification. 1H NMR (250 MHz, CDCl3, , ppm): 0.84 (t, 3H, J = 6.7 Hz), 1.21 – 1.41 (overlapping peaks with maximum at 1.33 ppm, 20H), 1.99 (t, 2H, J = 7.3 Hz), 3.93–4.08 (overlapping peaks, 4H), 6.89 (d, 1H, J = 3.7 Hz), 7.06 (d, 3H, J = 3.7 Hz),7.17 (d, 1H, J = 3.7Hz), 7.49 (d, 1H, J = 3.7Hz).

13

C NMR (125 MHz, CDCl3): δ

[ppm] 14.06, 22.54, 23.64, 24.73, 29.24, 31.70, 40.54, 64.99, 84.14, 108.95, 124.05, 124.73, 125.13, 136.72, 137.90, 144.12, 146.44. Calcd (%) for C23H33BO4S2: C, 61.60; H, 7.42; S, 14.30. Found: C, 61.43; H, 7.36; S, 14.38. tris{4-[5'-(2-hexyl-1,3-dioxolan-2-yl)-2,2'-bithien-5-yl]phenyl}amine (4c). 4c was obtained as described for compound 4a using compound 3c (4.4 g, 9.8 mmol), tris(4-bromophenyl)amine (1,26 g, 2.61 mmol) and Pd(PPh3)4 (340 mg, 0.29 mmol). The crude product was purified by column chromatography on silica gel (eluent toluene) to give pure compound 4c (2.32 g, 74%) as yellow solid. 1H NMR (250 MHz, CDCl3, Me4Si): δ [ppm] 0.85 (t, 9H, J = 6.7 Hz), 1.18-1.46 (overlapping peaks, 24H,), 2.00 (m, M =5, 6H), 3.93–4.08 (overlapping peaks, 12H), 6.89 (d, 3H, J = 3.7 Hz), 7.02 (d, 3H, J = 3.7 Hz), 7.08 (d, 3H, J = 3.7 Hz), 7.10–7.17 (overlapping peaks, 9H), 7.48 (d, 6H, J = 8.5 Hz). 13C NMR (125 MHz, CDCl3): δ [ppm] 14.07, 22.56, 23.69, 29.27, 31.73, 40.57, 65.00, 109.01, 123.09, 123.11, 124.40, 124.44, 125.10, 126.50, 128.94, 136.11, 136.97, 142.65, 145.66, 146.40. Calcd (%) for C69H75NO6S6: C, 68.68; H, 6.26; N, 1.16; S, 15.94. Found: C, 68.89; H, 6.29; N, 1.08; S, 15.75. HRESIMS: found m/z1205.3910; calculated for [M]+ 1205.3910. 1,1',1''-[nitrilotris(4,1-phenylene-2,2'-bithiene-5',5-diyl)]triheptan-1-one (5c). 5c was obtained as described for compound 5a using compound 4c (2.2 g, 1.8 mmol) and 5.47 mL of 1M HCl. After the completeness of the reaction the organic phase was separated, washed with water and filtered off to give pure product (1.92 g, 98%) as orange crystals. 1H NMR (250 MHz, CDCl3, Me4Si): δ [ppm] 0.88 (t, 9H, J = 6.7 Hz), 1.22-1.45 (overlapping peaks, 18H), 1.74 (m, M=5, 6H, J = 7.3 Hz), 2.86 (t, 6H, J = 7.3 Hz) 7.11–7.18 (overlapping peaks, 9H), 7.20 (d, 3H, J = 3.7 Hz), 7.27 (d, 3H, J = 4.3 Hz ), 7.52 (d, 6H, J = 8.5 Hz), 7.59 (d, 3H, J = 4.3 Hz). Calcd (%) for C63H63NO3S6: C, 70.42; H, 5.91; N, 1.30; S, 17.90. Found: C, 71.10; H, 5.94; N, 1.19; S, 17.61.

HRESIMS: found m/z 1074.33194; calculated for [M+H]+ 1074.33205. tris{4-[5'-(1,1-dicyanohept-1-en-2-yl)-2,2’-bithien-5-yl]phenyl}amine

-

N(Ph-2T-DCN-Hex)3. N(Ph-2T-DCN-Hex)3 was obtained as described for compound N(Ph-2T-DCN-Me)3 using compound 5c (1.78 g, 1.7 mmol) and malononitrile(1.31 g, 19.9 mmol). The crude product was purified by column chromatography on silica gel (eluent toluene). Further purification included precipitation of the product from its THF solution with toluene and hexane to give pure product in84% isolated yield as a black solid (1.7 g, 84%). 1H NMR (250 MHz, CDCl3, Me4Si): δ [ppm] 0.89 (t, 9H, J = 6.7 Hz), 1.26-1.38 (overlapping peaks, 12H), 1.40-1.51 (overlapping peaks, 6H), 1.7 (m, M=5, 6H, J = 7.3 Hz), 2.92 (t, 6H, J = 7.3 Hz), 7.16 (d, 6H, J = 8.5 Hz), 7.23 (d, 3H, J = 3.7 Hz), 7.27 (d, 3H, J = 4.3 Hz), 7.35 (d, 3H, J = 3.7 Hz), 7.51 (d, 6H, J = 8.5 Hz), 7.95 (d, 3H, J = 4.3 Hz). 13C NMR (125 MHz, CDCl3): δ [ppm] 13.97, 22.42, 29.19, 30.44, 31.26, 37.50, 113.87, 114.68, 123.83, 124.55, 124.78, 126.88, 127.64, 128.45, 133.76, 135.07, 135.15, 146.20, 146.72, 146.84, 166.32. Calcd (%) for C72H63N7S6: C, 70.96; H, 5.21; N, 8.04; S, 15.79. Found: C, 71.15; H, 5.31; N, 7.97; S, 15.52. HRESIMS: found m/z 1217.3349; calculated for [M+H]+ 1217.3464.

1-(2,2'-bithien-5-yl)tridecan-1-one (1d). 1d was obtained as described for compound 1a using 5-bromo-2,2'-bithiophene (8.73 g, 36 mmol) and magnesium (0.82 g, 36mmol) and tridecanoylchloride (8.28 g, 36 mmol) and freshly prepared Li2MnCl4 (1.1 mmol). After completeness of the reaction the reaction mixture was poured slowly into ice water and stirred for 1 h. The precipitating solid was isolated by filtration, washed with H2O and dried. After recrystallization from heptane 9.3 g (71%) of pure 1d was isolated. 1

H NMR (250 MHz, CDCl3, Me4Si): 0.87 (t, J = 6.7 Hz, 3H), 1.25 – 1.40 (overlapping

peaks, 18H), 1.73 (m, M = 5, 2H, J = 7.1 Hz,), 2.85 (t, 2H, J = 7.1 Hz), 7.04 (dd, 1H, J1 = 3.7, J2 = 1.1 Hz), 7.15 (d, 1H, J = 4.3 Hz), 7.28-7.33 (overlapping peaks, 2H), 7.58 (d, 1H, J = 4.3 Hz). 13C NMR (125 MHz, CDCl3): δ [ppm] 14.11, 22.67, 24.91, 29.33, 29.41, 29.46, 29.59, 29.61, 29.63, 31.89, 39.04, 124.06, 125.49, 126.33, 128.18, 132.49, 136.40, 142.32, 145.25, 193.28. Calcd (%) for C21H30OS2: C, 69.56; H, 8.34; S, 17.69. Found: C, 69.40; H, 8.11; S, 17.51.

2-(2,2'-bithien-5-yl)-2-dodecyl-1,3-dioxolane (2d). 2d was obtained by similar technique as described for compound 2a using compound 1d (8.0 g, 22.0 mmol), p-TosH (1.37 g, 7.2 mmol), ethylene glycol (55 g, 88 mol) and toluene (225 mL). It was purified by a column chromatography on silica gel (eluent toluene)to give pure product (4.5 g, 50%) as a colorless liquid. 1H NMR (250 MHz, CDCl3, , ppm): 0.86 (t, J = 6.7 Hz, 3H), 1.16 – 1.31 (overlapping peaks, 18H), 1.40 (m, M = 5, 2H, J = 7.1 Hz), 1.99 (t, 2H, J = 7.1 Hz), 3.92–4.09 (overlapping peaks, 4H), 6.88 (d, 1H, J = 3.7 Hz), 6.97 (dd, 1H, J1 = 3.7, J2 = 1.2 Hz), 7.01 (d, 1H, J = 3.7 Hz), 7.12 (d, 1H, J = 3.7 Hz), 7.18 (d, 1H, J = 4.3 Hz).

13

C NMR (125 MHz, CDCl3): δ [ppm] 14.10, 22.67, 23.71,

29.33, 29.50, 29.53, 29.61, 31.89, 40.55, 64.97, 109.00, 123.33, 123.51, 124.27, 124.99, 127.74, 136.87, 137.39, 145.72. Calcd (%) for C23H34O2S2: C, 67.93; H, 8.43; S, 15.77. Found: C, 68.25; H, 8.64; S, 15.52. 2-[5'-(2-dodecyl-1,3-dioxolan-2-yl)-2,2'-bithien-5-yl]-4,4,5,5-tetramethyl-1,3,2-dio xaborolane (3d). 3d was obtained as described for compound 3a using compound 2d (8.99 g, 22.1 mmol) and 2.5 M solution of butyllthium (8.84 mL, 22.1 mmol) in hexane and IPTMDOB (4.51 mL, 22.1 mmol) to give pure compound 3d (11.42 g, 97%) as green-blue crystals. The product was used in the subsequent synthesis without further purification. 1H NMR (250 MHz, CDCl3, , ppm): 0.86 (t, 3H, J = 6.7 Hz), 1.22 – 1.44 (overlapping peaks with maximum at 1.34 ppm, 32H), 1.98 (t, 2H, J = 7.3 Hz), 3.93–4.08 (overlapping peaks, 4H), 6.88 (d, 1H, J = 3.7 Hz), 7.06 (d, 3H, J = 3.7 Hz),7.17 (d, 1H, J = 3.7Hz), 7.49 (d, 1H, J = 3.7Hz).

13

C NMR (125 MHz, CDCl3): δ

[ppm] 14.09, 22.65, 23.68, 24.72, 29.32, 29.38, 29.48, 29.52, 29.57, 29.60, 31.88, 40.53, 64.98, 84.13, 108.97, 124.03, 124.72, 125.12, 136.73, 137.89, 144.12, 146.46. Calcd (%) for C29H45BO4S2: C, 65.40; H, 8.52; S, 12.04. Found: C, 65.73; H, 8.70; S, 11.88. tris{4-[5'-(2-dodecyl-1,3-dioxolan-2-yl)-2,2'-bithien-5-yl]phenyl}amine (4d). 4d was obtained as described for compound 4a using compound 3d (10.17 g, 19.1 mmol) and tris(4-bromophenyl)amine (2,6 g, 5,40 mmol) and Pd(PPh3)4 (662 mg, 0.6 mmol). The crude product was purified by column chromatography on silica gel (eluent toluene/hexane, 2:1) to give pure compound 4d (6.97 g, 89%) as yellow solid. 1H NMR (250 MHz, CDCl3, Me4Si): δ [ppm] 0.87 (t, J = 6.7 Hz, 9H), 1.23 – 1.32 (overlapping

peaks, 54H), 1.40 (m, M = 5, 6H, J = 7.1 Hz), 2.00 (t, 6H, J = 7.1 Hz), 3.96–4.06 (overlapping peaks, 12H), 6.89 (d, 3H, J = 3.7 Hz), 7.02 (d, 3H, J = 3.7 Hz), 7.08 (d, 3H, J = 3.7 Hz), 7.10–7.16 (overlapping peaks, 9H), 7.47 (d, 6H, J = 8.5 Hz).

13

C

NMR (125 MHz, CDCl3): δ [ppm] 14.11, 22.67, 23.73, 29.34, 29.50, 29.54, 29.62, 31.89, 40.55, 64.99, 109.01, 123.09, 124.39, 124.43, 125.10, 126.49, 128.94, 136.11, 136.97, 142.64, 145.65, 146.40. Calcd (%) for C87H111NO6S6: C, 71.61; H, 7.67; N, 0.96; S, 13.18. Found: C, 71.93; H, 7.80; N, 0.90; S, 13.01. 1,1',1''-[nitrilotris(4,1-phenylene-2,2'-bithiene-5',5-diyl)]tritridecan-1-one

(5d).

5d was obtained as described for compound 5a using compound 4d (6.5 g, 4.5 mmol) and 13.36 mL of 1M HCl. After the completeness of the reaction the organic phase was separated, washed with water and filtered off to give pure product (5.8 g, 98 %) as orange crystals. 1H NMR (250 MHz, CDCl3, Me4Si): δ [ppm] 0.87 (t, J = 6.7 Hz, 9H), 1.23 – 1.39 (overlapping peaks, 54H), 1.73 (m, M = 5, 6H, J = 7.1 Hz,), 2.85 (t, 6H, J = 7.1 Hz), 7.10–7.17 (overlapping peaks, 9H), 7.19 (d, 3H, J = 3.7 Hz), 7.27 (d, 3H, J = 4.3 Hz ), 7.51 (d, 6H, J = 8.5 Hz), 7.59 (d, 3H, J = 4.3 Hz).

13

C NMR (125 MHz,

CDCl3): δ [ppm] 14.10, 22.66, 24.94, 29.33, 29.35, 29.42, 29.47, 29.61, 29.63, 31.89, 39.04, 123.48, 123.74, 124.46, 126.53, 126.74, 128.66, 132.56, 135.01, 142.15, 144.83, 145.27, 146.65, 193.15. Calcd (%) for C81H99NO3S6: C, 73.31; H, 7.52; N, 1.06; S, 14.50. Found: C, 73.01; H, 7.40; N, 1.00; S, 14.31. N(Ph-2T-DCN-Dodec)3

was

obtained

as

described

for

compound

N(Ph-2T-DCN-Me)3 using compound 5d (5.45 g, 4.1 mmol) and malononitrile(3.25 g, 49.3 mmol). The crude product was purified by column chromatography on silica gel (eluent toluene/dichloromethane, 1:1). Further purification included precipitation of the product from its THF solution with toluene and hexane to give pure product in84% isolated yield as a black solid (5.15 g, 71%). 1H NMR (250 MHz, CDCl3, Me4Si): δ [ppm] 0.86 (t, J = 6.7 Hz, 9H), 1.22 – 1.33 (overlapped peaks, 48H), 1.45 (6H, m, M = 5, J = 6.7 Hz,), 1.70 (6H, m, M = 5, J = 7.1 Hz,), 2.92 (6H, t, J = 7.1 Hz), 7.15 (6H, d, J = 8.5 Hz), 7.23 (3H, d, J = 3.7 Hz), 7.26 (3H, d, J = 4.3 Hz), 7.34 (3H, d, J = 3.7 Hz), 7.52 (6H, d, J = 8.5 Hz), 7.94 (3H, d, J = 4.3 Hz). 13C NMR (125 MHz, CDCl3): δ [ppm] 14.11, 22.67, 29.14, 29.31, 29.38, 29.53, 29.58, 29.60, 30.47, 31.88, 37.51,

113.87, 114.68, 123.82, 124.55, 124.78, 126.88, 127.63, 128.45, 133.77, 135.08, 135.14, 146.20, 146.71, 146.84, 166.33. Calcd (%) for C90H99N7S6: C, 73.48; H, 6.78; N, 6.66; S, 13.08. Found: C, 73.34; H, 6.81; N, 6.64; S, 13.18. HRESIMS: found m/z 1469.6253; calculated for [M]+ 1469.6281.

1.3 Fabrication and characterization of the OSCs. AFM measurements were performed with a Nanosurf Easy Scan 2 in contact mode. Single carrier devices were fabricated and the dark current-voltage characteristics measured and analyzed in the space charge limited (SCL) regime following

the

references.[8]

The

structure

of

hole

only

devices

was

Glass/ITO/PEDOT:PSS/Active layer/PEDOT:PSS/Ag (100 nm). For the electron only devices, the structure was Glass/ITO/AZO/Active layer/Ca (15 m)/Ag (80 nm), where both Ca and Ag were evaporated. The reported mobility data are average values over the two cells of each sample at a given film composition. Grazing incidence X-Ray diffraction and X-Ray reflectivity experiments were performed on DESY synchrotron radiation source (Hamburg, Germany), using PETRA III P-09 beamline. Incident X-Ray beam with the energy of 15 keV probed polymer films had the size of 200 µm and 50 µm in vertical and horizontal directions respectively. Reflected radiation was monitored by 2D Perkin Elmer 1621 CN3-ETIS detector as well as by point avalance photodiode recorder. During the experiment, samples were kept under helium atmosphere to reduce radiation damage. X-Ray reflectivity data were analyzed using StochFit program which utilizes stochastic fitting methods to model specular reflectivity curves. The obtained distributions of electron density were afterwards interpolated by slab models with subsequent solution of scattering problem and following reconstruction of reflectivity curves. The electron density  = 2/e where e is the classical electron radius equal to 2.814·10-5Å, and  is the dispersion coefficient[9], as well as thickness d and

roughness R of monolayers were calculated. All the devices were fabricated in the normal architecture. Photovoltaic devices were fabricated by doctor-blading on indium tin oxide (ITO)-covered glass substrates (from Osram). These substrates were cleaned in toluene, water, acetone, and isopropyl alcohol. After drying, the substrates were bladed with 50 nm PEDOT:PSS (HC Starck, PEDOT PH-4083). Photovoltaic layers, consisting of four different small molecules and PC70BM in 1:2 wt.% ratios were dissolved at different concentrations in dichlorobenzene (ODCB) and bladed on top of PEDOT:PSS layer. The thickness of active layers is ca. 90 nm.Finally, a calcium/silver top electrode of 15/80 nm thickness was evaporated. The typical active area of the investigated devices was 10.4 mm2. The current-voltage characteristics of the solar cells were measured under AM1.5G irradiation on an OrielSol 1A Solar simulator (100 mW/cm2). The EQE was detected with cary 500 Scan UV-Vis-NIR Spectrophotometer under monochromatic illumination, which was calibrated with a mono-crystalline silicon diode. For TPV measurements, devices were directly connected to an oscilloscope in open-circuit conditions (1MX). The device was illuminated with white light to set the desired Voc, at this point equilibrium between charge formation, due to the illumination with light, and charge recombination was reached.

2. Results and discussion 2.1 GPC, 1H-, and 13C- spectroscopy, elemental analysis data

O S S

7.25

Chloroform-d

1.06

2.00

7.5 No. 1

1.04 7.0

(ppm) 7.25

(Hz) 2176.2

3.14 6.5 Height 0.0621

6.0 No. 1

Annotation Chloroform-d

5.5

5.0 4.5 Chemical Shift (ppm)

(ppm) 7.25

No. 1 2 3 4 5

(ppm) [2.53 .. 2.54] [7.02 .. 7.06] [7.14 .. 7.17] [7.28 .. 7.33] [7.56 .. 7.59]

4.0 Value 3.145 1.039 1.023 2.000 1.058

3.5

Absolute Value 2.03630e+9 6.72780e+8 6.62148e+8 1.29506e+9 6.85397e+8

Figure S1. 1H NMR spectrum of compound 1a in CDCl3

3.0

2.5

124.10

77.42 77.00 76.58

133.31 128.21 126.46

Chloroform-d

26.49

O S

200 No. 1 2 3 4 5 6 7 8 9 10 11 12 13

180 (ppm) 26.49 76.58 77.00 77.42 124.10 125.60 126.46 128.21 133.31 136.29 142.35 145.74 190.39

160

(Hz) 1999.5 5780.0 5811.8 5843.9 9366.4 9480.0 9545.3 9676.9 10061.7 10286.7 10744.2 11000.1 14370.4

Height 0.6544 0.8902 0.8962 0.8852 0.9810 0.9485 1.0000 0.9603 0.9786 0.1180 0.1254 0.1292 0.1631

136.29

145.74 142.35

190.39

S

140 No. 1


120

100 Chemical Shift (ppm)

80

60

(ppm) [76.58 .. 77.42]

Figure S2. 13C NMR spectrum of compound 1a in CDCl3

40

20

0

O O S S

2

Chloroform-d

1.94 7.0 No. 1

4.00 6.5


6.0 (ppm) 7.25

5.5 No. 1 2 3 4 5 6

5.0 (ppm) [1.75 .. 1.82] [3.96 .. 4.11] [6.91 .. 6.96] [6.96 .. 7.04] [7.10 .. 7.16] [7.17 .. 7.22]

4.5

4.0 3.5 3.0 Chemical Shift (ppm)

Value 3.017 4.000 0.950 1.942 0.971 0.950

Absolute Value 1.31526e+7 1.74376e+7 4.14251e+6 8.46496e+6 4.23400e+6 4.14281e+6

3.02 2.5

2.0


1.5

1.0

0.5

0

O O O

S S

B O

7.25

Chloroform-d

1.06

2.00

7.5 No. 1

1.04 7.0

(ppm) 7.25

(Hz) 2176.2

3.14 6.5 Height 0.0621

6.0 No. 1


5.5


(ppm) 7.25

No. 1 2 3 4 5

(ppm) [2.53 .. 2.54] [7.02 .. 7.06] [7.14 .. 7.17] [7.28 .. 7.33] [7.56 .. 7.59]

4.0 Value 3.145 1.039 1.023 2.000 1.058

3.5

Absolute Value 2.03630e+9 6.72780e+8 6.62148e+8 1.29506e+9 6.85397e+8


3.0

2.5

24.72

O O 64.96

O

S B

S

O

150

140

No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

(ppm) 24.72 27.43 64.96 76.58 77.00 77.42 84.15 107.00 124.06 124.83 124.89 136.79 137.90 144.02 146.91

27.43

84.15 107.00

136.79

146.91 144.02

137.90

124.89 124.06

77.42 77.00 76.58

Chloroform-d

130 (Hz) 1865.8 2070.7 4903.4 5779.7 5811.8 5843.9 6351.7 8076.0 9363.7 9421.6 9426.2 10324.7 10408.2 10870.1 11088.6

120 Height 1.0000 0.2779 0.6321 0.4057 0.4173 0.4044 0.2733 0.1031 0.2878 0.2539 0.3027 0.0750 0.2582 0.0656 0.0828

110 No. 1

100 Annotation Chloroform-d

90

80 70 Chemical Shift (ppm)

60

50

40

(ppm) [76.58 .. 77.42]

Figure S5. 13C NMR spectrum of compound 3ain CDCl3

30

20

10

0

O O S

2.49

DMSO-d6

S

N

S O O

S

S

S O O

6.00 8.0 No. 1

7.5 (ppm) 2.49

6.03 7.0 (Hz) 622.8

12.00 6.5 Height 0.6191

6.0 No. 1

5.5 Annotation DMSO-d6

5.0 (ppm) 2.49

4.5 4.0 3.5 Chemical Shift (ppm) No. 1 2 3 4 5 6 7 8

(ppm) [1.66 .. 1.71] [3.87 .. 4.05] [6.99 .. 7.04] [7.07 .. 7.13] [7.16 .. 7.18] [7.26 .. 7.29] [7.38 .. 7.44] [7.58 .. 7.67]

9.06 3.0 Value 9.061 12.004 3.016 6.033 3.125 3.028 3.000 6.001

2.5

2.0

Absolute Value 3.69130e+6 4.89020e+6 1.22884e+6 2.45779e+6 1.27299e+6 1.23346e+6 1.22214e+6 2.44478e+6

Figure S6. 1H NMR spectrum of compound 4a in DMSO-d6

1.5

1.0

0.5

0

Chloroform-d 77.42 77.00 76.58

O O S

64.97

S

N

S O

S

S

O

S O

150 No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

140

(ppm) 27.41 64.97 76.58 77.00 77.42 107.02 123.08 123.11 124.37 124.52 124.85 126.48 128.88 135.98 137.02 142.72 146.08 146.37

130

(Hz) 2069.2 4903.4 5779.9 5811.8 5843.7 8077.3 9289.7 9291.9 9387.0 9398.7 9423.3 9546.5 9727.7 10263.4 10342.1 10771.9 11025.9 11047.6

27.41

107.02

124.37 123.11

128.88

137.02 135.98

146.37 146.08 142.72

126.48 124.85

O

120 Height 0.4041 0.6924 0.9776 1.0000 0.9741 0.2359 0.2535 0.3213 0.3172 0.2586 0.3240 0.3257 0.2009 0.1813 0.1849 0.2066 0.1807 0.2147

110 No. 1

100


90


60

50

40

(ppm) [76.58 .. 77.42]

Figure S7. 13C NMR spectrum of compound 4ain CDCl3

30

20

10

0

2.49

DMSO-d6

6.09 8.0 No. 1

7.5 (ppm) 2.49

6.58 7.0 (Hz) 622.8

9.44 6.5 Height 0.8834

6.0 No. 1

5.5 Annotation DMSO-d6

5.0 (ppm) 2.49

4.5 4.0 3.5 Chemical Shift (ppm) No. 1 2 3 4 5 6

(ppm) [2.50 .. 2.53] [7.10 .. 7.17] [7.28 .. 7.33] [7.35 .. 7.44] [7.52 .. 7.62] [7.74 .. 7.82]

3.0 Value 9.436 6.584 3.020 6.045 6.094 3.000

2.5

2.0

Absolute Value 4.06224e+6 2.83458e+6 1.30006e+6 2.60223e+6 2.62334e+6 1.29151e+6

Figure S8. 1H NMR spectrum of compound 5a in DMSO-d6

1.5

1.0

0.5

0

2.49

DMSO-d6

NC

CN

CN

S

S

NC

S S N

S

S NC NC

3.00 8.0 No. 1

6.08

6.00

7.5 (ppm) 2.49

(Hz) 622.8

9.03

7.0

6.5

Height 1.0000

6.0 No. 1

5.5

Annotation DMSO-d6

5.0 (ppm) 2.49

4.5 4.0 3.5 Chemical Shift (ppm) No. 1 2 3 4 5 6 7

(ppm) [2.63 .. 2.73] [7.08 .. 7.16] [7.43 .. 7.49] [7.49 .. 7.53] [7.53 .. 7.57] [7.58 .. 7.66] [8.01 .. 8.08]

3.0 Value 9.028 5.996 3.075 3.107 3.089 6.077 3.000

2.5

2.0

1.5

Absolute Value 1.53191e+7 1.01741e+7 5.21723e+6 5.27306e+6 5.24244e+6 1.03117e+7 5.09072e+6

Figure S9. 1H NMR spectrum of N(Ph-2T-DCN-Me)3 in DMSO-d6

1.0

0.5

0

124.57

NC

CN

CN

S

S

NC

S S N

126.93

77.29 76.87 76.44

Chloroform-d

S

S NC

160 No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

(ppm) 22.88 76.44 76.87 77.29 113.69 114.28 123.82 124.57 126.93 127.55 128.62 133.83 134.96 135.90 146.36 146.74 146.96 160.70

150

140

(Hz) 1727.3 5769.8 5801.9 5833.7 8580.9 8625.4 9345.8 9402.2 9580.5 9627.2 9707.9 10101.5 10186.7 10257.7 11046.9 11075.7 11092.5 12129.1

130

Height 0.4189 0.6755 0.6820 0.6682 0.1741 0.1763 0.3637 1.0000 0.6342 0.3838 0.2091 0.1713 0.3826 0.1579 0.1925 0.1702 0.2530 0.1689

22.88

123.82 114.28 113.69

128.62

135.90 133.83

146.96 146.74 146.36

160.70

134.96

127.55

NC

120 No. 1

110


100

90 80 70 Chemical Shift (ppm)

60

50

40

(ppm) [76.44 .. 77.29]

Figure S10. 13C NMR spectrum of N(Ph-2T-DCN-Me)3 in CDCl3

30

20

10

0

7.25

Chloroform-d

O S S

1.02 2.03 1.01 7.5 No. 1

(ppm) 7.25

2.02

7.0

6.5

(Hz) 1813.5

Height 1.0000

6.0 No. 1

5.5

5.0


4.5 4.0 3.5 Chemical Shift (ppm) (ppm) 7.25

No. 1 2 3 4 5 6 7 8

(ppm) [0.85 .. 0.92] [1.27 .. 1.42] [1.68 .. 1.80] [2.82 .. 2.90] [7.02 .. 7.07] [7.14 .. 7.18] [7.28 .. 7.33] [7.56 .. 7.60]

3.0 Value 3.014 6.248 2.028 2.019 1.007 1.000 2.028 1.023

2.03 2.5

2.0


Figure S11. 1H NMR spectrum of compound 1cin CDCl3

6.25 1.5

3.01 1.0

0.5

0

O S

200 No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

180 (ppm) 14.03 22.48 24.85 28.99 31.58 39.02 76.58 77.00 77.42 124.06 125.48 126.33 128.18 132.48 136.38 142.32 145.24 193.27

160

(Hz) 1059.0 1696.9 1875.4 2188.3 2383.8 2944.9 5779.7 5811.8 5843.8 9363.5 9470.8 9534.9 9674.5 9999.5 10293.6 10742.4 10962.2 14587.3

Height 0.8162 0.8974 0.9101 0.9814 0.9315 0.9517 0.8886 0.9006 0.8767 0.9655 1.0000 0.9453 0.9957 0.9426 0.2042 0.2422 0.2139 0.2828

136.38

145.24 142.32

193.27

14.03

31.58 28.99 24.85 22.48

39.02

Chloroform-d 77.42 77.00 76.58

125.48 124.06

132.48 128.18

S

140 No. 1



80

60

(ppm) [76.58 .. 77.42]

Figure S12. 13C NMR spectrum of compound 1cin CDCl3

40

20

0

7.25

Chloroform-d

O O S S

water

1.38 7.5 No. 1

(ppm) 7.25

4.35

7.0

6.5

(Hz) 1813.5

Height 1.0000

6.0 No. 1 2

5.5

5.0

Annotation water Chloroform-d

2.13

4.5 4.0 3.5 Chemical Shift (ppm) (ppm) 1.55 7.25

No. 1 2 3 4 5 6 7 8 9

(ppm) [0.80 .. 0.92] [1.22 .. 1.45] [1.95 .. 2.03] [3.93 .. 4.07] [6.87 .. 6.91] [6.97 .. 7.00] [7.00 .. 7.04] [7.11 .. 7.14] [7.17 .. 7.21]

3.0 Value 3.309 8.645 2.134 4.348 1.000 0.730 1.381 1.006 1.113

2.5

2.0

Absolute Value 1.51929e+7 3.96933e+7 9.79977e+6 1.99608e+7 4.59119e+6 3.35386e+6 6.34115e+6 4.61726e+6 5.10865e+6

Figure S13. 1H NMR spectrum of compound 2c in CDCl3.

8.65 1.5

3.31 1.0

0.5

0

64.97

O O S

170 No. 1 2 3 4 5 6 7 8 9 10

(ppm) 14.06 22.55 23.68 29.25 31.71 40.55 64.97 76.58 77.00 77.42

160

150

(Hz) 1061.4 1702.0 1787.0 2207.9 2393.6 3060.8 4904.1 5779.9 5811.8 5843.7

14.06

22.55

137.38 136.86

145.71

108.98

40.55

77.42 77.00 76.58

Chloroform-d

23.68

31.71 29.25

127.75 125.00 123.52 123.34

S

140 Height 0.4842 0.5454 0.4667 0.5192 0.5367 0.4592 1.0000 0.4857 0.4863 0.4839

130 No. 11 12 13 14 15 16 17 18 19

120

(ppm) 108.98 123.34 123.52 124.28 125.00 127.75 136.86 137.38 145.71

110 (Hz) 8225.7 9309.1 9322.8 9380.7 9434.4 9642.3 10330.2 10368.8 10997.6

100 90 80 Chemical Shift (ppm) Height 0.2372 0.5063 0.5309 0.4888 0.4983 0.5245 0.1094 0.0964 0.1181

No. 1

70


60

50

(ppm) [76.58 .. 77.42]

Figure S14. 13C NMR spectrum of compound 2c in CDCl3.

40

30

20

10

O O O

S B

S

O

7.25

Chloroform-d

0.99 1.04 1.02 7.5 No. 1

(ppm) 7.25

7.0 (Hz) 1813.5

4.27 6.5 Height 0.1714

6.0 No. 1

5.5

5.0


2.07


No. 1 2 3 4 5 6 7 8

(ppm) [0.80 .. 0.89] [1.21 .. 1.41] [1.94 .. 2.03] [3.93 .. 4.07] [6.86 .. 6.91] [7.04 .. 7.10] [7.15 .. 7.20] [7.46 .. 7.54]

3.0 Value 3.149 20.586 2.074 4.271 1.024 1.000 1.042 0.991

2.5

2.0



20.59 1.5

3.15 1.0

0.5

0

24.73

O O O

S B

S

160 No. 1 2 3 4 5 6 7 8 9 10

150 (ppm) 14.06 22.54 23.64 24.73 29.24 31.70 40.54 64.99 76.58 77.00

140 (Hz) 1061.0 1701.3 1784.4 1866.5 2206.8 2392.8 3059.6 4905.0 5780.0 5811.8

108.95

14.06

40.54

22.54

31.70 29.24

77.42 77.00 76.58

125.13 124.73 124.05

136.72

146.44 144.12

137.90

84.14

Chloroform-d

64.99

O

130 Height 0.3240 0.3490 0.2535 1.0000 0.3039 0.3367 0.2308 0.4914 0.4258 0.4365

120 No. 11 12 13 14 15 16 17 18 19 20

110

(ppm) 77.42 84.14 108.95 124.05 124.73 125.13 136.72 137.90 144.12 146.44

100 (Hz) 5843.9 6350.8 8223.6 9363.0 9414.4 9444.9 10319.6 10408.2 10877.5 11053.3

90 80 70 Chemical Shift (ppm) Height 0.4240 0.3741 0.1900 0.2753 0.2650 0.2739 0.1218 0.2787 0.1053 0.1458

No. 1


60

50

40

(ppm) [76.58 .. 77.42]


30

20

10

0

7.25

Chloroform-d

O

O O

S S

O

S S N

S

S O O

6.01 9.35 8.0 No. 1

7.5 (ppm) 7.25

7.0 (Hz) 1813.5

12.03 6.5 Height 1.0000

6.0 No. 1

5.5 Annotation Chloroform-d

5.0


(ppm) 7.25

No. 1 2 3 4 5 6 7 8 9

(ppm) [0.80 .. 0.91] [1.22 .. 1.52] [1.93 .. 2.06] [3.94 .. 4.10] [6.87 .. 6.94] [7.00 .. 7.06] [7.07 .. 7.10] [7.10 .. 7.19] [7.45 .. 7.55]

6.00 3.0

2.5

2.0

Value 9.047 24.369 6.000 12.026 3.020 3.001 3.085 9.352 6.008



24.37 1.5

9.05 1.0

0.5

0

O

77.42 77.00 76.58

Chloroform-d

O O

S S

O

S S

31.73

S

S

65.00

O

14.07

22.56

N

150

No. 1 2 3 4 5 6 7 8 9 10 11 12

140

(ppm) 14.07 22.56 23.69 29.27 31.73 40.57 65.00 76.58 77.00 77.42 109.01 123.09

40.57

23.69

109.01

128.94

136.97 136.11

146.40 145.66 142.65

126.50 124.40 123.11

29.27

O

130

(Hz) 1061.9 1702.9 1788.3 2209.0 2394.6 3061.8 4906.1 5779.8 5811.8 5843.8 8228.1 9290.5

120

Height 0.7110 0.7316 0.4158 0.5706 0.6868 0.3275 0.6272 0.9829 1.0000 0.9767 0.5007 0.3505

110

100

No. 13 14 15 16 17 18 19 20 21 22 23

(ppm) 123.11 124.40 124.44 125.10 126.50 128.94 136.11 136.97 142.65 145.66 146.40


(Hz) 9292.2 9389.6 9392.5 9442.2 9548.0 9732.4 10273.6 10338.3 10766.7 10993.9 11050.2

Height 0.4262 0.4481 0.3703 0.3451 0.4285 0.3102 0.3024 0.3071 0.3228 0.3509 0.3210

No. 1

60

50


40

30

(ppm) [76.58 .. 77.42]


20

10

0

Chloroform-d

O

O S S S S N

S

S O

6.01 12.03 7.5

7.0

6.08 6.5

6.0

5.5

5.0


3.5

3.0

6.16 2.5


2.0

18.25 1.5

9.00 1.0

7.25

Chloroform-d

NC

CN

CN S S

CN

S S N

S

S NC NC

3.00

No. 1

6.08 6.18

8.0

7.5

7.0

(ppm) 7.25

(Hz) 1813.5

Height 1.0000

6.05 6.5

6.0 No. 1

5.5


5.0


(ppm) 7.25

No. 1 2 3 4 5 6 7 8 9 10 11

(ppm) [0.85 .. 0.92] [1.28 .. 1.38] [1.40 .. 1.51] [1.63 .. 1.77] [2.86 .. 2.98] [7.14 .. 7.19] [7.20 .. 7.24] [7.26 .. 7.29] [7.32 .. 7.38] [7.50 .. 7.57] [7.92 .. 7.99]

3.0 Value 9.832 12.787 5.996 6.429 6.054 6.177 2.920 3.008 3.034 6.082 3.000

6.43 12.79 2.5

2.0

1.5

Absolute Value 1.63588e+7 2.12749e+7 9.97713e+6 1.06967e+7 1.00729e+7 1.02779e+7 4.85921e+6 5.00561e+6 5.04857e+6 1.01196e+7 4.99154e+6

Figure S20. 1H NMR spectrum of N(Ph-2T-DCN-Hex)3in CDCl3.

9.83 1.0

0.5

0

170 No. 1 2 3 4 5 6 7 8 9 10 11 12

160 (ppm) 13.97 22.42 29.19 30.44 31.26 37.50 76.58 77.00 77.42 113.87 114.68 123.83

150 (Hz) 1054.7 1692.6 2203.2 2297.5 2359.8 2830.8 5779.8 5811.8 5843.8 8594.5 8655.8 9346.1

140

130

120

Height 0.4774 0.4801 0.3444 0.1964 0.4332 0.1183 0.9790 1.0000 0.9698 0.1172 0.1446 0.1473

No. 13 14 15 16 17 18 19 20 21 22 23 24

(ppm) 124.55 124.78 126.88 127.64 128.45 133.76 135.07 135.15 146.20 146.72 146.84 166.32

110 (Hz) 9400.9 9418.4 9576.4 9633.8 9695.1 10096.2 10194.8 10200.8 11034.8 11073.8 11083.1 12553.6

13.97

22.42

37.50

114.68 113.87

135.07 133.76 128.45 126.88 123.83 124.55

146.84 146.72 146.20

166.32

29.19

31.26

77.42 77.00 76.58

Chloroform-d

100 90 80 70 Chemical Shift (ppm) Height 0.2153 0.1739 0.2318 0.1573 0.1737 0.1772 0.2083 0.1633 0.1885 0.1812 0.1730 0.2032

No. 1


60

50

40

30

(ppm) [76.58 .. 77.42]

Figure S21. 13C NMR spectrum N(Ph-2T-DCN-Hex)3 in CDCl3.

20

10

0

O S S

7.25

Chloroform-d

1.07 1.97 1.03 7.5 No. 1

(ppm) 7.25

7.0 (Hz) 2176.2

2.21 6.5 Height 0.0485

6.0 No. 1

5.5

5.0



No. 1 2 3 4 5 6 7 8

(ppm) [0.84 .. 0.91] [1.25 .. 1.37] [1.69 .. 1.77] [2.82 .. 2.88] [7.02 .. 7.06] [7.14 .. 7.17] [7.28 .. 7.33] [7.57 .. 7.59]

3.0 Value 3.146 18.152 2.368 2.209 1.028 1.008 1.972 1.066

2.37 2.5

2.0


Figure S22. 1H NMR spectrum of 1din CDCl3.

18.15 1.5

3.15 1.0

0.5

0

29.33

O S

180 No. 1 2 3 4 5 6 7 8 9 10 11 12

(ppm) 14.11 22.67 24.91 29.33 29.41 29.46 29.59 29.61 29.63 31.89 39.04 76.58

160 (Hz) 1065.0 1711.0 1880.5 2214.0 2219.7 2223.8 2233.5 2234.9 2236.6 2407.0 2946.6 5780.2

Height 0.5096 0.5473 0.5169 1.0000 0.5518 0.5580 0.6480 0.7031 0.6323 0.5450 0.5141 0.5123

140 No. 13 14 15 16 17 18 19 20 21 22 23

14.11

24.91 22.67

31.89

39.04

77.43 77.01 76.58

125.49 124.06

Chloroform-d

136.40

145.25 142.35

193.28

132.49 128.18

29.63 29.61

S

(ppm) 77.01 77.43 124.06 125.49 126.33 128.18 132.49 136.40 142.35 145.25 193.28

120 (Hz) 5812.2 5844.2 9364.0 9471.5 9535.2 9674.9 9999.7 10295.2 10744.0 10963.3 14588.7

100 80 Chemical Shift (ppm) Height 0.5262 0.5060 0.5443 0.5482 0.5055 0.5392 0.5002 0.1334 0.1579 0.1343 0.1725

No. 1


60 (ppm) [76.58 .. 77.43]

Figure S23. 13C NMR spectrum of 1din CDCl3.

40

20

0

O O S S

7.25

Chloroform-d

1.96 7.5 No. 1

7.0 (ppm) 7.25

4.11 6.5 (Hz) 1813.5

6.0 Height 0.3074

5.5 No. 1

5.0


4.5

2.04


(ppm) 7.25

No. 1 2 3 4 5 6 7 8 9

(ppm) [0.81 .. 0.92] [1.16 .. 1.31] [1.33 .. 1.43] [1.92 .. 2.05] [3.92 .. 4.09] [6.86 .. 6.91] [6.95 .. 7.03] [7.09 .. 7.15] [7.16 .. 7.21]

3.0 Value 3.053 18.257 2.012 2.036 4.113 1.000 1.958 0.999 1.005

2.5

2.0



18.26 3.05 1.5

1.0

0.5

0

29.61 64.97

77.42 76.99 76.57

Chloroform-d

O O S

150 No. 1 2 3 4 5 6 7 8 9 10 11

14.10

23.71

22.67

29.33

31.89

137.39 136.87

145.72

109.00

40.55

123.51 123.33

127.74 124.99

S

140 (ppm) 14.10 22.67 23.71 29.33 29.50 29.53 29.61 31.89 40.55 64.97 76.57

130 (Hz) 1064.5 1710.8 1789.9 2213.5 2226.2 2229.1 2234.7 2406.8 3060.3 4903.9 5779.3

120 Height 0.4632 0.4698 0.3891 0.5366 0.4740 0.4980 1.0000 0.4992 0.3619 0.8014 0.8212

110 No. 12 13 14 15 16 17 18 19 20 21 22

100

(ppm) 76.99 77.42 109.00 123.33 123.51 124.27 124.99 127.74 136.87 137.39 145.72

90

(Hz) 5811.2 5843.2 8227.0 9308.5 9322.4 9379.6 9434.0 9641.5 10330.8 10369.7 10998.7

80 70 60 Chemical Shift (ppm) Height 0.8357 0.8184 0.2361 0.4326 0.4665 0.4174 0.4361 0.4321 0.1299 0.1217 0.1690

No. 1


50

40

(ppm) [76.57 .. 77.42]


30

20

10

0

O

O O

S S

B O

7.25

Chloroform-d

1.00 1.02 1.00 7.5 No. 1

(ppm) 7.25

7.0 (Hz) 2176.2

4.30 6.5 Height 0.0289

6.0

5.5 No. 1

5.0


2.11


No. 1 2 3 4 5 6 7 8

(ppm) [0.84 .. 0.89] [1.22 .. 1.44] [1.95 .. 2.01] [3.96 .. 4.04] [6.88 .. 6.90] [7.05 .. 7.09] [7.17 .. 7.20] [7.47 .. 7.52]

3.0 Value 3.072 32.947 2.108 4.299 1.002 1.001 1.015 1.000

2.5

2.0



32.95 1.5

3.07 1.0

0.5

0

24.72 29.60

77.41 76.99 76.56

Chloroform-d

O O O

S S

B

150 No. 1 2 3 4 5 6 7 8 9 10 11 12

(ppm) 14.09 22.65 23.68 24.72 29.32 29.48 29.52 29.57 29.60 31.88 40.53 64.98

14.09

22.65

29.57

31.88 40.53

108.97

136.73

146.46 144.12

137.89

125.12 124.72 124.03

84.13

64.98

O

140

130

(Hz) 1063.8 1709.8 1787.0 1866.1 2212.8 2225.0 2228.2 2232.0 2234.2 2406.1 3059.1 4904.8

120

Height 0.3203 0.3355 0.2307 1.0000 0.3595 0.3181 0.3577 0.3676 0.6611 0.3474 0.2147 0.4600

110 No. 13 14 15 16 17 18 19 20 21 22 23 24

(ppm) 76.56 76.99 77.41 84.13 108.97 124.03 124.72 125.12 136.73 137.89 144.12 146.46

100 (Hz) 5778.8 5810.7 5842.7 6350.0 8224.6 9361.8 9413.5 9444.1 10320.4 10407.4 10878.0 11054.2

90 80 70 Chemical Shift (ppm) Height 0.7321 0.7481 0.7275 0.3970 0.2149 0.2680 0.2572 0.2675 0.1266 0.2604 0.1103 0.1572

No. 1

60


50

40

(ppm) [76.56 .. 77.41]


30

20

10

0

O O O

S S

O

S S N

S

S O O

7.25

Chloroform-d

6.03 9.233.00 7.5 No. 1

(ppm) 7.25

7.0 (Hz) 2176.2

12.32 6.5 Height 0.0318

6.0

5.5 No. 1

5.0

4.5


(ppm) 7.25

6.24

4.0 3.5 Chemical Shift (ppm) No. 1 2 3 4 5 6 7 8 9 10

(ppm) [0.83 .. 0.91] [1.23 .. 1.32] [1.37 .. 1.45] [1.96 .. 2.04] [3.96 .. 4.06] [6.88 .. 6.93] [7.01 .. 7.06] [7.07 .. 7.10] [7.10 .. 7.16] [7.46 .. 7.52]

3.0 Value 9.057 54.883 6.282 6.236 12.324 3.000 3.005 3.193 9.231 6.034

2.5

2.0

Absolute Value 4.78790e+9 2.90138e+10 3.32088e+9 3.29664e+9 6.51530e+9 1.58597e+9 1.58883e+9 1.68820e+9 4.87969e+9 3.18997e+9


54.88 1.5

9.06 1.0

0.5

0

77.42 76.99 76.57

29.62

Chloroform-d

O O O

S S

O

S S N

S

S

40.55

14.11

22.67 23.73

109.01

128.94

136.97 136.11

146.40 145.65 142.64

126.49 124.39 123.09

64.99

31.89

O

29.34

O

150

140

130

120

No. 1 2 3 4 5 6 7 8 9 10 11 12 13

(ppm) 14.11 22.67 23.73 29.34 29.50 29.54 29.62 31.89 40.55 64.99 76.57 76.99 77.42

(Hz) 1065.2 1711.2 1791.1 2214.2 2227.0 2229.8 2235.6 2407.3 3060.8 4905.5 5779.3 5811.2 5843.2

Height 0.4299 0.4492 0.2562 0.4880 0.4222 0.4793 1.0000 0.4660 0.2053 0.3778 0.9383 0.9710 0.9416

110 No. 14 15 16 17 18 19 20 21 22 23 24 25

100 (ppm) 109.01 123.09 124.39 124.43 125.10 126.49 128.94 136.11 136.97 142.64 145.65 146.40

90

(Hz) 8228.0 9290.9 9389.0 9391.4 9441.9 9547.2 9732.1 10273.3 10338.2 10765.9 10993.1 11049.6

80 70 Chemical Shift (ppm) Height 0.2974 0.2917 0.3054 0.2590 0.2092 0.2659 0.1848 0.1754 0.1794 0.1891 0.2004 0.1659

No. 1

60


50

40

(ppm) [76.57 .. 77.42]


30

20

10

0

O

O

S S

S S N

S

S

Chloroform-d 7.25

O

6.09 9.11

No. 1

6.11

7.5

7.0

6.5

(ppm) 7.25

(Hz) 2176.2

Height 0.0873

6.0 No. 1

5.5

5.0



No. 1 2 3 4 5 6 7 8 9

(ppm) [0.81 .. 0.95] [1.23 .. 1.39] [1.69 .. 1.80] [2.81 .. 2.89] [7.10 .. 7.17] [7.17 .. 7.20] [7.25 .. 7.28] [7.47 .. 7.54] [7.56 .. 7.61]

3.0 Value 8.978 55.334 6.231 6.111 9.109 3.091 3.063 6.094 3.000

6.23 2.5

2.0



55.33 1.5

8.98 1.0

0.5

0

29.61

77.41 76.99 76.57

Chloroform-d

O

O

S S

S S

29.63 29.33

N

S

146.65 145.27 144.83 142.15 135.01 132.56 128.66

193.15

180 No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14

(ppm) 14.10 22.66 24.94 29.33 29.35 29.42 29.47 29.61 29.63 31.89 39.04 76.57 76.99 77.41

14.10

39.04

126.74 124.46 123.74 123.48

24.94

22.66

31.89

S O

(Hz) 1064.3 1710.5 1882.7 2213.5 2215.2 2220.2 2224.1 2234.7 2236.6 2407.0 2946.3 5779.3 5811.0 5843.0

160 Height 0.5464 0.5903 0.4093 0.6725 0.5770 0.5327 0.5737 0.8493 0.6982 0.5796 0.3185 0.9807 1.0000 0.9869

140 No. 15 16 17 18 19 20 21 22 23 24 25 26 27

(ppm) 123.48 123.74 124.46 126.53 126.74 128.66 132.56 135.01 142.15 144.83 145.27 146.65 193.15

120 (Hz) 9320.0 9340.0 9394.1 9550.1 9566.2 9710.9 10005.5 10190.1 10728.9 10931.8 10964.8 11068.6 14578.6

100 Chemical Shift (ppm) Height 0.2338 0.2821 0.3293 0.2341 0.3451 0.2241 0.2629 0.2343 0.2627 0.2500 0.2249 0.2406 0.2616

No. 1

80


60 (ppm) [76.57 .. 77.41]


40

20

0

CN S NC

CN

CN

S

S S N

7.25

Chloroform-d S

S NC CN

3.00

No. 1

6.09 6.13

8.0

7.5

7.0

(ppm) 7.25

(Hz) 1813.5

Height 0.4110

6.14 6.5

6.0 No. 1

5.5


5.0


(ppm) 7.25

No. 1 2 3 4 5 6 7 8 9 10 11

(ppm) [0.80 .. 0.92] [1.22 .. 1.33] [1.40 .. 1.51] [1.63 .. 1.76] [2.86 .. 2.98] [7.14 .. 7.19] [7.22 .. 7.25] [7.26 .. 7.28] [7.33 .. 7.37] [7.51 .. 7.57] [7.93 .. 7.98]

6.14 48.38 10.00

3.0

2.5

2.0

Value 9.995 48.383 6.108 6.142 6.136 6.135 3.037 3.106 3.053 6.085 3.000

Absolute Value 8.95661e+6 4.33559e+7 5.47296e+6 5.50400e+6 5.49884e+6 5.49725e+6 2.72147e+6 2.78298e+6 2.73622e+6 5.45312e+6 2.68830e+6

1.5

1.0

Figure S32. 1H NMR spectrum of N(Ph-2T-DCN-DoDec)3 in CDCl3.

0.5

0

29.53

77.43 77.01 76.58

Chloroform-d

CN S NC

CN

CN

S

S

14.11

S

22.67

31.88

N

29.31

S

S NC

(ppm) 14.11 22.67 29.14 29.31 29.38 29.53 29.58 29.60 30.47 31.88 37.51 76.58 77.01 77.43 113.87

150 (Hz) 1065.0 1710.8 2199.3 2212.5 2217.3 2228.9 2233.0 2234.4 2299.6 2406.3 2831.4 5780.2 5812.2 5844.2 8594.4

140

130

Height 0.5449 0.5855 0.4262 0.6199 0.5043 0.7814 0.6831 0.6303 0.2094 0.6080 0.1422 0.9767 1.0000 0.9710 0.1437

120 No. 16 17 18 19 20 21 22 23 24 25 26 27 28 29

(ppm) 114.68 123.82 124.55 124.78 126.88 127.63 128.45 133.77 135.08 135.14 146.20 146.71 146.84 166.33

110

29.14 37.51

114.68 113.87

146.84 146.20

166.33

160 No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

135.14 135.08 133.77 128.45 126.88 123.82 124.55

CN

100

(Hz) 8655.9 9345.7 9401.0 9418.1 9576.3 9633.3 9695.3 10096.6 10195.4 10200.4 11034.7 11073.2 11083.3 12554.0


Height 0.1832 0.1792 0.2606 0.2039 0.2655 0.1794 0.2202 0.2281 0.2689 0.1923 0.2476 0.2077 0.2248 0.2257

No. 1


60

50

40

30

20

(ppm) [76.58 .. 77.43]

Figure S33. 13C NMR spectrum of N(Ph-2T-DCN-DoDec)3 in CDCl3.

2.2 Thermogravimetric analysis (TGA) and differential scanning calorimetry

10

0

(DSC) data

Residual weight, %

100

80

1 2

60

3 4

40

20

0 100

Figure

S34.

200

300

Thermogravimetric

400

analysis

500

of

600 T, °C

1)

N(Ph-2T-DCN-Me)3;

2)

N(Ph-2T-DCN-Et)3; 3) N(Ph-2T-DCN-Hex)3; 4) N(Ph-2T-DCN-Dodec)3 in inert atmosphere (nitrogen flow).

100

1 2

Residual weight, %

80

3

60

4

40

20

0 100

200

300

400

500

600

T, C

Figure S35.Thermogravimetric analysis of 1) N(Ph-2T-DCN-Me)3; 2) N(Ph-2T-DCN-Et)3; 3) N(Ph-2T-DCN-Hex)3; 4) N(Ph-2T-DCN-Dodec)3 in air flow.

|Cp|, Jg/K 4 3

3

Endo

2

1

2

1

0 50

100

150

200

o

T, C

Figure S36. DSC scans of 1) N(Ph-2T-DCN-Me)3; 2) N(Ph-2T-DCN-Et)3; 3) N(Ph-2T-DCN-Hex)3; 4) N(Ph-2T-DCN-Dodec)3. For the sake of simplicity, curves are shifted along heat flow axis. Table S1. Parameters of glass transition in the compounds studied by DSC method. Small molecule

Tg, °C

Cp, J/g·K

N(Ph-2T-DCN-Me)3

152

0.21

N(Ph-2T-DCN-Et)3

114

0.24

N(Ph-2T-DCN-Hex)3

64

0.25

N(Ph-2T-DCN-Dodec)3

31

0.26

2.3 Wide-angle and small-angle measurements of X-Ray scattering With

increasing

temperature,

mesophase

reflection

of

compound

N(Ph-2T-DCN-Dodec)3 shifts to wider angles, d-spacing was being decreased to 29.5 Å at 60°C. Such change corresponds to thermal expansion coefficient  = 6.6·10-4 K-1 which is rather common for liquid crystalline materials and is due to shrinking of alkyl end chains. With increasing temperature a transition to isotropic phase is observed near 100°C. Mesophase order has not restored on cooling. Unfortunately structural data is not enough for unambiguous identification of the mesophase formed in as-received samples of compound N(Ph-2T-DCN-Dodec)3.

However some remarks could be made. According to the results of molecular modeling, the radius of molecular disc of N(Ph-2T-DCN-Dodec)3 is 26.5 Å provided the alkyl chains are in extended conformation, which coincides with great precise with diameter of columns if calculated from small-angle reflection d-spacing observed. Such supramolecular aggregate formed by twelve molecules is shown on (insert on Figure S38). Their arms are shifted relatively to each other by several degrees providing  stacking between neighboring arms of different molecules forming helical aggregate. However, as wide reflections as well as higher orders of 10 columnar reflection are not observed, such interpretation is open for further studies.

6

Intensity, a.u.

5 4 4

3 2

3

1

2 1

0 1.0

1.5

2.0

2.5

-1

s, Å

Figure S37. WAXS patterns of 1) N(Ph-2T-DCN-Me)3; 2) N(Ph-2T-DCN-Et)3; 3) N(Ph-2T-DCN-Hex)3; 4) N(Ph-2T-DCN-Dodec)3. For the sake of simplicity, scans are shifted along Intensity axis.

Intensity, a.u.

N(Ph-2T-DCN-Dodec)3 N(Ph-2T-DCN-Dodec)3 N(Ph-2T-DCN-Dodec)3 N(Ph-2T-DCN-Dodec)3*

5 4 3 3* 2

N(Ph-2T-DCN-Me)3 1 N(Ph-2T-DCN-Et)3 0.1

0.2

0.3

0.4

0.5

s, Å-1

Figure S38. SAXS patterns of 1) N(Ph-2T-DCN-Et)3; 2) N(Ph-2T-DCN-Me)3; N(Ph-2T-DCN-Dodec)3 at room temperature (3), 40 oC (4), 60oC (5), and at room temperature after heating to isotropic phase (3*). For the sake of simplicity, scans are shifted along Intensity axis. An insert shows simulated structure of the column formed by N(Ph-2T-DCN-Dodec)3 at low temperatures.

2.4 cyclic voltammetry (CV) measurements.

Figure S39. Electrochemical oxidation curve of N(Ph-2T-DCN-Me)3.

Figure S40. Electrochemical reduction curve (first peak) of N(Ph-2T-DCN-Me)3.

Figure S41. Electrochemical oxidation curve of N(Ph-2T-DCN-Et)3.

Figure S42. Electrochemical reduction curve (first peak) of N(Ph-2T-DCN-Et)3.

Figure S43. Electrochemical oxidation curve of N(Ph-2T-DCN-Hex)3.

Figure S44. Electrochemical reduction curve (first peak) of N(Ph-2T-DCN-Hex)3.

Figure S45. Electrochemical oxidation curve of N(Ph-2T-DCN-Dodec)3.

Figure S46. Electrochemical reduction curve (first peak) of N(Ph-2T-DCN-Dodec)3.

lg I

0.03

0.04

0.05

s, Å-1

Figure S47. X-Ray Reflectivity curve for mixtures of star-shaped oligothiophenes with PC70BM. Arrows show minima observed.

(a) 3 .0

N(Ph-2T-DCN-Me)3

2 .5

2 .0

2 .0

N(Ph-2T-DCN-Et)3

q Z, A

-1

2 .5

-1

q Z, A

(b) 3 .0

1 .5

1 .5

1 .0

1 .0

0 .5

0 .5

0 .0

0 .0 0 .0

0 .5

1 .0

q XY , A

(c)

1 .5

0 .0

-1

0 .5

1 .0

q XY , A

1 .5

-1

lg I

N(Ph-2T-DCN-Et)3 N(Ph-2T-DCN-Me)3 1.0

Figure

1.5

2.0

2.5

3.0

s, Å-1

S48. Grazing Incidence X-Ray scattering measurements’ data of

N(Ph-2T-DCN-Me)3:PC70BM and N(Ph-2T-DCN-Et)3:PC70BM blend films.


2.5 Current density-voltage (I-V) curves of solar cells

0 N(Ph-2T-DCN-Me)3 : PC70BM (1:1) N(Ph-2T-DCN-Me)3 : PC70BM (1:1.5) N(Ph-2T-DCN-Me)3 : PC70BM (1:2) N(Ph-2T-DCN-Me)3 : PC70BM (1:2.5)

-2

-4

-6

-8 0.0

0.2

0.4 0.6 Voltage (V)

0.8

1.0

Figure 49. Current density-voltage (J-V) curves of solar cells based on N(Ph-2T-DCN-Me)3:PC70BM with different ratios, under the illumination of AM 1.5, 100 mA/cm2.

Normalized Absorbance (a.u.)

2.6Absorption spectrum curves of blends.

N(Ph-2T-DCN-Me)3 : PC70BM (1:2) N(Ph-2T-DCN-Et)3 : PC70BM (1:2) N(Ph-2T-DCN-Hex)3 : PC70BM (1:2) N(Ph-2T-DCN-Dodec)3 : PC70BM (1:2)

0.8

0.6

0.4

0.2

0.0 400

500

600

700

Wavelength (nm)

Figure 50.Absorption spectrum curves of the small molecules: PC70BM blends with

the same weight ratio of 1:2.

2.7Space charge limited current (SCLC) method for measuring mobilities.

5

10

4

10

a

5

10

3

10


1

10

0

10

N(Ph-2T-DCN-Dodec)3 Fitting curves N(Ph-2T-DCN-Me)3

-1

10

-2

10

-4

N(Ph-2T-DCN-Dodec)3

0

1

2

3

4 Vin (V)

5

6

2

10

N(Ph-2T-DCN-Dodec)3 Fitting curves N(Ph-2T-DCN-Me)3

10

-3

10


10

1


10

electron only mobility N(Ph-2T-DCN-Me)3

3

J(A/m2)

J(A/m2)

4

10

hole only mobility N(Ph-2T-DCN-Me)3

2

10

b


0

10

N(Ph-2T-DCN-Dodec)3

-1

10

7

0

1

2

3

4 Vin (V)

5

6

7

Figure S51. Hole only mobility (a) and electron only mobility (b) of N(Ph-2T-DCN-Me)3:PC70BM, N(Ph-2T-DCN-Et)3:PC70BM,N(Ph-2T-DCN-Hex)3:PC70BM, N(Ph-2T-DCN-Dodec)3:PC70BM (1:2, wt%) blends.

and

2.8Transient Photovoltage (TPV) measurement

Figure S52. Small perturbation charge carrier lifetime measured by TPV for the N(Ph-2T-DCN-Me)3:PC70BM (1:2, wt%) based devcies.

Figure S53. Small perturbation charge carrier lifetime measured by TPV for the N(Ph-2T-DCN-Et)3:PC70BM (1:2, wt%) based devcies.

Figure S54. Small perturbation charge carrier lifetime measured by TPV for the N(Ph-2T-DCN-Hex)3:PC70BM (1:2, wt%) based devcies.

Figure S55. Small perturbation charge carrier lifetime measured by TPV for the N(Ph-2T-DCN-Dodec)3:PC70BM (1:2, wt%) based devcies.

0.5

a



2 0

N(Ph-2T-DCN-Me)3

-2

N(Ph-2T-DCN-Et)3

-4

N(Ph-2T-DCN-Hex)3

-6

N(Ph-2T-DCN-Dodec)3

-8 -10 -12

b 0.0

-0.5

-1.0

N(Ph-2T-DCN-Me)3 N(Ph-2T-DCN-Et)3

-1.5


-2.0

-14 -3

-2

-1

Voltage (V)

0

1

-3

-2

-1

0

1

Voltage (V)

Figure S56. Current characteristics of BHJ solar cells under (a) 1 sun illumination and (b) in the dark.

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