Feb 13, 2015 - intriguing advantages such as flexibility, low cost, and solution processability. Development of organic conjugated polymers with balanced ...
Article pubs.acs.org/cm
Balanced Ambipolar Organic Thin-Film Transistors Operated under Ambient Conditions: Role of the Donor Moiety in BDOPV-Based Conjugated Copolymers Xu Zhou, Na Ai, Zi-Hao Guo, Fang-Dong Zhuang, Yu-Sheng Jiang, Jie-Yu Wang,* and Jian Pei* Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China S Supporting Information *
ABSTRACT: Organic field-effect transistors (OFETs) are receiving an increased amount of attention because of their intriguing advantages such as flexibility, low cost, and solution processability. Development of organic conjugated polymers with balanced ambipolar carrier transportation operated under ambient conditions, in particular, is considered to be one of the central issues in OFETs. In this work, the 3,7-bis[(E)-2oxoindolin-3-ylidene]-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran2,6-dione (BDOPV) unit as a good acceptor unit was copolymerized with three donor moieties, thieno[3,2-b]thiophene (TT), benzo[1,2-b:4,5-b′]dithiophene (BDT), and benzo[1,2-b:4,5-b′]diselenophene (BDSe), to construct three donor−acceptor (D−A) conjugated polymers, BDOPV−TT, BDOPV−BDT, and BDOPV−BDSe. Photophysical and electrochemical properties of all the polymers were characterized. The fabrication of OFETs using three polymers as the active layers demonstrated that all the three polymers showed balanced ambipolar transport properties tested under ambient conditions, which is of great importance in complementary circuits. In particular, both electron and hole mobilities of BDOPV−TT were achieved above 1 cm2 V−1 s−1 under ambient conditions (1.37 and 1.70 cm2 V−1 s−1, respectively), showing great potential in balanced ambipolar OFETs.
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of >1 cm2 V−1 s−1 (all tested in nitrogen) were based on diketopyrrolopyrrole (DPP) as an acceptor unit.18−21 To create OFETs operated under ambient conditions with high electron and hole mobilities, new types of polymers containing acceptors other than DPP are being pursued. 3,7-Bis[(E)-2oxoindolin-3-ylidene]-3,7-dihydrobenzo[1,2-b:4,5-b′]difuran2,6-dione (BDOPV) as a new acceptor was developed in our group to construct polymers that show perfect OFET performance with an electron mobility of 1 cm2 V−1 s−1.22−25 For instance, polymer BDOPV-2T exhibited n-type transport behavior with a high electron mobility of 1.74 cm2 V−1 s−1 under ambient conditions; however, upon being exposed to oxygen, BDOPV-2T displayed ambipolar transport behaviors, which maintained high electron mobilities while hole mobilities significantly increased to 0.47 cm2 V−1 s−1.23 These results demonstrate that the BDOPV unit is a promising acceptor for the construction of new polymers for high-performance ambipolar charge transport. In this work, we report the synthesis and characterization of three solution-processable ambipolar polymers, BDOPV−TT, BDOPV−BDT, and BDOPV−BDSe. BDOPV acts as a strong
INTRODUCTION Conjugated polymers with the advantages of low cost, largearea printing, mechanical flexibility, and tunable optoelectronic properties are of extensive scientific interest for application in organic field-effect transistors (OFETs).1−5 The performance of OFETs has been remarkably improved recently because of the rational design of molecular structures and optimization of device fabrication.6,7 In particular, the development of ambipolar OFETs that operate under ambient conditions is very important for further fabrication of single-component organic logic circuits and light-emitting transistors, as well as a fundamental understanding of electron versus hole transport in polymer films.8−13 Recently, the properties of ambipolar polymer semiconductors, in which both hole and electron can be transported, have been improved significantly.14,15 Nevertheless, most ambipolar OFETs were fabricated and tested under nitrogen or in vacuum. Very few polymers are known to be operated under ambient conditions and generally exhibit relatively low hole/electron mobilities (
