Yuan Yi, Kumar Pankaj, Ngai Jenner H L, Gao Xiguang, Li Xu, Liu Haitao, Wang Jinliang, Li Yuning
Department of Chemical Engineering and Waterloo Institute of Nanotechnology (WIN), University of Waterloo, 200 University Ave West, Waterloo, ON, N2L 3G1, Canada.
Institute of Chemistry, Henan Academy of Sciences, 56 Hongzhuan Road, Jinshui District, Zhengzhou, Henan, 450002, China.
Macromol Rapid Commun. 2022 Oct;43(20):e2200325. doi: 10.1002/marc.202200325. Epub 2022 May 15.
Organic semiconductors inherently have a low dielectric constant and hence high exciton binding energy, which is largely responsible for the rather low power conversion efficiency of organic solar cells as well as the requirements to achieve delicate bulk-heterojunction nanophase separation in the active layer. In this study, methyl acrylate as a weakly electron-withdrawing side chain for the electron rich thiophene to prepare a new building block, methyl thiophene-3-acrylate (TA), with increased polarity is used. A wide bandgap polymer PBDT-TA synthesized using TA and a benzodithiophene (BDT) monomer shows increased dielectric constant and reduced exciton binding energy compared to the analogous polymer PBDT-TC, which is made of BDT and methyl thiophene-3-carboxylate (TC). An organic solar cell device based on PBDT-TA:ITIC also achieves a higher power conversion efficiency of 10.47% than that of the PBDT-TC:ITIC based solar cell (9.68%). This work demonstrates the effectiveness of using acrylate side chains to increase the dielectric constant, reduce the exciton binding energy, and enhance the solar cell efficiency of polymer semiconductors.
有机半导体本质上具有低介电常数，因此具有高激子结合能，这在很大程度上导致了有机太阳能电池的功率转换效率相当低，以及在活性层中实现精细的体相异质结纳米相分离的要求。在本研究中，使用丙烯酸甲酯作为富电子噻吩的弱吸电子侧链，以制备具有增加极性的新型结构单元甲基噻吩-3-丙烯酸酯（TA）。与由苯并二噻吩（BDT）和甲基噻吩-3-羧酸酯（TC）制成的类似聚合物PBDT-TC相比，使用TA和苯并二噻吩（BDT）单体合成的宽带隙聚合物PBDT-TA显示出增加的介电常数和降低的激子结合能。基于PBDT-TA:ITIC的有机太阳能电池器件也实现了比基于PBDT-TC:ITIC的太阳能电池（9.68%）更高的10.47%的功率转换效率。这项工作证明了使用丙烯酸酯侧链来增加介电常数、降低激子结合能以及提高聚合物半导体太阳能电池效率的有效性。
