Enhancing the Performance of Organic Solar Cells by Prolonging the Lifetime of Photogenerated Excitons

• DOI: 10.1002/adma.202003164
• Publication Date: 2020-11-09T08:21:31Z
• Authors: Qingxin Guo; Yahui Liu; Ming Liu; Hao Zhang; Xiquan Qian; Jinjin Yang; Jing Wang; Wenyue Xue; Qian Zhao; Xinjun Xu; Wei Ma; Zheng Tang; Yunliang Li; Zhishan Bo
• Keywords: Acceptor; Active layer; Quantum yield

Abstract Exciton lifetime (τ) is crucial for the migration of excitons to donor/acceptor interfaces subsequent charge separation in organic solar cells (OSCs); however, obvious prolongation τ has rarely been achieved. Here, by introducing a solid additive 9‐fluorenone‐1‐carboxylic acid (FCA) into active layer, which comprises nonfullerene acceptor, 3,9‐bis(2‐methylene‐((3‐(1,1‐dicyanomethylene)‐6/7‐methyl)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene (IT‐M), substantially prolonged from 491 928 ps, together with increases fluorescence intensity and quantum yield. Time‐resolved transient infrared spectra indicate presence an intermolecular vibrational coupling between electronic excited state IT‐M ground FCA, first observed here can suppress internal conversion process. IT‐M‐based OSCs display improved short‐circuit current fill factor after addition FCA. Thus, power efficiency increased, particularly devices large ratio 1:4, whose increased 56%. This study describes novel method, also applicable other acceptors, further improving performance without affecting their morphology light absorption properties.