Reducing Energy Loss and Morphology Optimization Manipulated by Molecular Geometry Engineering for H

• 作 者: Guodong Xu Huan Rao Xunfan Liao Youdi Zhang Yuming Wang Zhi Xing Ting Hu Licheng Tan Lie Chen Yiwang Chen
• 机 构: College of Chemistry/Institute of Polymers and Energy Chemistry(IPEC),Nanchang University,Nanchang,J
• 出 处: 中国化学（英文版）
• 发表日期: 2020年12期

Molecular geometry engineering is an effective strategy to control the micromorphology and molecular energy level in organic photovoltaics(OPVs).Two novel copolymers based on alkylsilyl-and chloride-functionalized benzodithiophene(BDT)were de-signed and synthesized for wide bandgap copolymer donor materials in OPVs.It was found that the two copolymers exhibited distinctly different proper-ties in active layer when blended with fullerene-free acceptor IT-4F.The chloride-functionalized copolymer PBDTCI-TZ with deeper molecular energy level and better coplanar structure induced more ordered aggregation in blend film.Thus,the device based on PBDTCI-TZ exhibits better energy alignment with IT-4F and smaller radiative recombination.Furthermore,the non-radiative recombination of PBDTCI-TZ:IT-4F based device is about 45 mV lower than the PBDTSi-TZ:IT-4F based device,contributing to a lower energy loss(Eloss),and a higher open-circut voltage(Voc).As a result,the devices based on the blend of PBDTCI-TZ:IT-4F exhibit a high power conversion efficiency(PCE)of up to 12.2％ with a high Voc of 0.837 V,higher than that of PBDTSi-TZ:IT-4F,of which the PCE is 11.2％ with a Voc of 0.781 V.