Wide Bandgap Polymer Donors Based on Succinimide-Substituted Thiophene for Non-Fullerene Organic Solar Cells.

The advent of non-fullerene acceptors (NFAs) has greatly improved the photovoltaic performance of organic solar cells (OSCs). However, to compete with other solar cell technologies, there is a pressing need for accelerated research and development of improved NFAs as well as their compatible wide bandgap polymer donors. In this study, a novel electron-withdrawing building block, succinimide-substituted thiophene (TS), is utilized for the first time to synthesize three wide bandgap polymer donors: PBDT-TS-C5, PBDT-TSBT-C12, and PBDTF-TSBT-C16. These polymers exhibit complementary bandgaps for efficient sunlight harvesting and suitable frontier energy levels for exciton dissociation when paired with the extensively studied NFA, Y6. Among these donors, PBDTF-TSBT-C16 demonstrates the highest hole mobility and a relatively low highest occupied molecular orbital (HOMO) energy level, attributed to the incorporation of thiophene spacers and electron-withdrawing fluorine substituents. OSC devices based on the blend of PBDTF-TSBT-C16:Y6 achieve the highest PCE of 13.21%, with a J sc of 26.83 mA cm -2 , a V oc of 0.80 V, and an FF of 0.62. Notably, the V oc ×J sc product reaches 21.46 mW cm -2 , demonstrating the potential of TS as an electron acceptor building block for the development of high-performance wide bandgap polymer donors in OSCs. This article is protected by copyright. All rights reserved.