High-mobility low-bandgap conjugated copolymers based on indacenodithiophene and thiadiazolo[3,4-c]pyridine units for thin film transistor and photovoltaic applications
作者:Ying Sun、Shang-Chieh Chien、Hin-Lap Yip、Yong Zhang、Kung-Shih Chen、David F. Zeigler、Fang-Chung Chen、Baoping Lin、Alex K.-Y. Jen
DOI:10.1039/c1jm11564b
日期:——
Two new semiconducting polymers based on indacenodithiophene and thiadiazolo[3,4-c]pyridine units were synthesized viaStille coupling polymerization. The polymers, PIDTPyT and PIDTDTPyT, exhibited main absorption bands in the range of 550–800 nm while their absorption maxima were located at around 700 nm in films. With two additional thiophene spacers, PIDTDTPyT showed a broader absorption band but a 20 nm blue-shifted maximum peak compared to that of PIDTPyT. Both of the polymers possess low bandgaps (∼1.6 eV) and deep energy levels for both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Organic field-effect transistors (OFETs) device measurements indicate that PIDTPyT and PIDTDTPyT have high hole carrier mobilities of 0.066 and 0.045 cm2 V−1s−1, respectively, with the on/off ratio on the order of 106. Bulk heterojunction photovoltaic devices consisting of the copolymers and PC71BM gave power conversion efficiencies (PCE) as high as 3.91% with broadband photo-response in the range of 300–800 nm. The relationships between the photovoltaic performance and film morphology, energy levels, hole mobilities are discussed.
通过斯蒂尔偶联聚合法合成了两种基于茚并二噻吩和噻二唑并[3,4-c]吡啶单元的新型半导体聚合物。聚合物 PIDTPyT 和 PIDTDTPyT 在 550-800 纳米范围内显示出主要吸收带,而它们在薄膜中的吸收最大值位于 700 纳米左右。与 PIDTPyT 相比,带有两个额外噻吩间隔的 PIDTDTPyT 的吸收带更宽,但最大峰值蓝移了 20 纳米。这两种聚合物都具有较低的带隙(1.6 eV)和较深的最高占位分子轨道(HOMO)和最低未占位分子轨道(LUMO)能级。有机场效应晶体管(OFET)器件测量结果表明,PIDTPyT 和 PIDTDTPyT 的空穴载流子迁移率分别高达 0.066 和 0.045 cm2 V-1s-1,导通/截止比约为 106。由共聚物和 PC71BM 组成的块状异质结光伏器件的功率转换效率(PCE)高达 3.91%,在 300-800 纳米范围内具有宽带光响应。本文讨论了光伏性能与薄膜形态、能级和空穴迁移率之间的关系。