Enhancing the photovoltaic performance of chlorobenzene-cored unfused electron acceptors by introducing S•••O noncovalent interaction

The chlorination strategy has been proven an effective approach for designing efficient conjugated electron donor (ED) or acceptor (EA) units for organic solar cells (OSCs). However, up to now, the chlorination strategy has only been used in the design of unfused electron acceptors (UFAs) by modifying the terminal 2-(3-oxo-2,3-dihydminden-1-ylidene (IC) groups. Due to the steric hindrance of Cl atom, the chlorobenzene (CB)-centered UFAs have not been reported. Herein, two novel CB cored UFAs named 2Cl-4F and Cl-4F were designed and synthesized, the steric effect drawbacks of Cl-atoms was successfully overcome by involving S center dot center dot center dot O noncovalent interaction. The C-shape Cl-4F based OSCs with PM6 as donor, yields a power conversion efficiency (PCE) of 11.71%, significantly higher than that of the S-shape 2Cl-4F-based device (3.95%). This work reveals that appropriate central-core chlorine engineering is a simple and effective approach to develop novel efficient UFAs.

Automated summary

The chlorination strategy is an effective approach for designing efficient electron donor or acceptor units for organic solar cells. However, it has only been used for the design of unfused electron acceptors so far. In this study, the steric hindrance caused by chlorine atoms was successfully overcome by introducing S···O noncovalent interaction, leading to the development of novel efficient UFAs.