Supplementary Information
Homogeneous Photosensitization of Complex TiO2 Nanostructures for Efficient Solar Energy Conversion Jingshan Luo,1, ‡ Siva Krishna Karuturi,2, ‡ Lijun Liu,2 Liap Tat Su,2 Alfred Iing Yoong Tok,2 and Hong Jin Fan1,* 1
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore 2 School of Materials Science and Engineering, Nanyang Technological University, 639798 Singapore ‡ These authors contributed equally to this work. * Corresponding author. Email:
[email protected]
Diffused reflctance (a.u.)
0.90 0.75 0.60
TiIO TiIO/ZnSe TiIO/ZnCdSe1 TiIO/ZnCdSe2 TiIO/CdSe
0.45 0.30 0.15 0.00 300
400
500
600
700
800
Wavelength (nm)
Figure S1 UV-vis diffuse reflection spectra of samples showing the transition from pristine TiO2 inverse opal (TIO) via ZnSe-coated TIO, and intermediate phase ZnCeSe-coated TIO, to final CdSe-coated TIO.
1
(a)
(b)
2
(c)
Figure S2 SEM images of the cross section of the TiO2 inverse opal before (a) and after (b) CdSe sensitization by the ALDIER method (atomic layer deposition + ion exchange reaction). (c) A closer-view of the bottom part of the inverse opal film.
3
18 16
TiIO 90 C TiIO 120 C TiIO 140 C
2
Current density (mA/cm )
(a)
14 12 10 8 6 4
dark
2 0 -1.0
0.0
0.5
Potential vs Ag/AgCl (V) 20
2
Current density (mA/cm )
(b)
-0.5
16
12
8
4
0 90
100
110
120
130
140
0
Temperature ( C) Figure S3. Effect of the ion exchange reaction temperature to the photocurrent.
4
(a) TiIO
(c) TiIO CdSe 6 cycles
(b) TiIO CdSe 3 cycles
(d) TiIO CdSe 9 cycles
Figure S4 SEM images of the CdSe-coated TiO2 structure by the commonly used successive ionic layer adsorption and reaction (SILAR) method. The cycle number denotes the number of SILAR steps.
5
Diffused reflectance (%)
(a)
100
80
TiIO TiIO/CdSe 3 cycles TiIO/CdSe 6 cycles TiIO/CdSe 9 cycles
60
40
20
0 300
500
600
700
800
Wavelength (nm) 8
2
Current density (mA/cm )
(b)
400
TiIO/CdSe 3 cycles TiIO/CdSe 6 cycles TiIO/CdSe 9 cycles
6
4
2
dark 0 -1.0
-0.5
0.0
0.5
Potential VS. Ag/AgCl Figure S5 Characterization of the CdSe-coated TiO2 inverse opal (TIO) via the common SILAR method. (a) UV-vis diffuse reflection spectra. (b) J-V curves. The cycle number denotes the number of SILAR steps.
6
(a) TiO2 NP
(b) TiO2 NP 25 cycles
(d) TiO2 NP TiO2 NP ZnSe TiO2 NP CdSe
0.6 0.5 0.4 0.3 0.2 0.1 0.0 300
400
500
600
Wavelength (nm)
700
800
Current density (mA/cm2)
Diffused reflectance (a.u.)
(c)
15
TiO2 NP 25 cycles dark TiO2 NP 25 cycles light
12 9 6 3 0 -1.0
-0.5
0.0
0.5
Potential vs Ag/AgCl
Figure S6 Application of the ALDIER method to TiO2 P25 nanoparticles film. (a) SEM image of the pristine nanparticle film, (b) SEM image of the film after the CdSe coating by ALDIER. (c) UV-vis diffuse reflection spectra. The corresponding photographs of the sample are shown in inset. (d) J-V curve of the sample after SILIAR with 25 ALD ZnO cycles.
7
(a)
(b)
Figure S7 SEM images of the CdSe-coated TiO2 nanorods by ALDIER. (a) Pristine nanorods, (b) after the coating.
8
