Understanding energetic disorder in electron-deficient-core-based non-fullerene solar cells

• 作者: Beibei Qiu Can Zhu Chujun Zhang Fangfang Cai Feng Gao Hang Yin Honggang Chen Hongjian Peng Huotian Zhang Jidong Zhang Jun Yuan Junhang Yang Lei Meng Qingya Wei Rui Zhang Shukong So Sin Hang Cheung Wei Liu Weifang Liu Ye Liu Yingping Zou Yongfang Li
• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2020,（8）
• 所属期刊栏目: ARTICLES
• 页码范围: 1159-1168
• 页数: 10页
• 语种: 英文

摘要

Recent advances in material design for organic solar cells (OSCs) are primarily focused on developing near-infrared non-fullerene acceptors,typically A-DA'D-A type acceptors (where A abbreviates an electron-withdrawing moiety and D,an electron-donor moiety),to achieve high external quantum efficiency while maintaining low voltage loss.However,the charge transport is still constrained by unfavorable molecular conformations,resulting in high energetic disorder and limiting the device performance.Here,a facile design strategy is reported by introducing the "wing" (alkyl chains) at the terminal of the DA'D central core of the A-DA'D-A type acceptor to achieve a favorable and ordered molecular orientation and therefore facilitate charge carrier transport.Benefitting from the reduced disorder,the electron mobilities could be significantly enhanced for the "wing"-containing molecules.By carefully changing the length of alkyl chains,the mobility of acceptor has been tuned to match with that of donor,leading to a minimized charge imbalance factor and a high fill factor (FF).We further provide useful design strategies for highly efficient OSCs with high FF.