Asymmetric Isomer Effects in Benzo[c ][1,2,5]thiadiazole‐Fused Nonacyclic Acceptors: Dielectric Constant and Molecular Crystallinity Control for Significant Photovoltaic Performance Enhancement
Abstract
Herein, asymmetric isomer effects are systematically explored by designing and synthesizing two benzo[c][1,2,5]thiadiazole (BT)‐fused nonacyclic electron acceptors. By changing from BP6T‐4F to asymmetric ABP6T‐4F, significantly enhanced dielectric constant and inhibited excessive molecular aggregation and unfavorable edge‐on orientation could be achieved. The reduced exciton binding energy also facilitates a more efficient dissociation process in PM6:ABP6T‐4F compared to PM6:BP6T‐4F with the same energy offset. Moreover, the weaker crystallization behavior enables a significantly enhanced miscibility between PM6 and ABP6T‐4F than that between PM6 and BP6T‐4F, which leads to an optimized micromorphology with smooth surface, suitable domain size, and ordered π–π stacking. Organic solar cells (OSCs) based on PM6:ABP6T‐4F achieve a 15.8% power conversion efficiency (PCE), which is remarkably higher than that of PM6:BP6T‐4F‐based OSCs (6.4%). Furthermore, ternary devices are also fabricated considering good compatibility between ABP6T‐4F and CH1007 to deliver a PCE over 17%. This study reveals the effectiveness and great potential of asymmetric isomerization strategy in regulating molecular properties, which will provide guidance for the future design of non‐fullerene acceptors.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 25, 2021
- Source ID
- 10.1002/adfm.202104369
Entities
People
- Alex K.‐y. Jen
- Baobing Fan
- Cheng Zhong
- Francis Lin
- Fujun Zhang
- Jie Min
- Jingdong Luo
- Jinhua Gao
- Qi Feng
- Rui Sun
- Wei Gao
- Xinhui Lu
- Xinxin Xia
- Zonglong Zhu
Organizations
- City University of Hong Kong
- National Natural Science Foundation of China
- Office of Naval Research
- The Chinese University of Hong Kong
- University of Washington
- Wuhan University