Poly(oligothiophene-alt-benzothiadiazole)s: Tuning the Structures of Oligothiophene Units toward High-Mobility “Black” Conjugated Polymers

• DOI: 10.1021/ma900906t
• Publication Date: 2009-07-20T11:28:40Z
• Authors: Wei Yue; Yun Zhao; Hongkun Tian; De Song; Zhiyuan Xie; Donghang Yan; Yanhou Geng; Fosong Wang
• Keywords: 01 natural sciences; 0104 chemical sciences

A series of donor−acceptor low-bandgap conjugated polymers, i.e., PTnBT (n = 2−6), composed alternating oligothiophene (OTh) and 2,1,3-benzothiadiazole (BT) units were synthesized by Stille cross-coupling polymerization. The number thiophene rings in OTh units, that is n, was tuned from 2 to 6. All these polymers display two absorption bands both solutions films with maxima depending on n. From solution film, spectra the exhibit a noticeable red shift. Both high- low-energy PT5BT PT6BT locate visible region, which are at 468 662 nm for 494 657 PT6BT. Consequently, their cover region between 400 800 nm, optical bandgaps 1.56 1.52 eV, respectively, renders them "black" polymers. Moreover, can form highly ordered thin field-effect mobilities up 2.46 × 10−2 1.40 cm2 V−1 s−1, respectively. Bulk-heterojunction polymer solar cells (PSCs) fabricated as donor materials 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-C-61 (PCBM) acceptor material exhibited power conversion efficiencies (PCEs) 0.93−2.23%. PSCs based high-mobility showed best device performance PCE 2.23%. Our results provide rational strategy design synthesis broad range.