P3HT-Based Organic Solar Cells with a Photoresponse to 1000 nm Enabled by Narrow Band Gap Nonfullerene Acceptors with High HOMO Levels
Ziqi Liang, Xiafei Cheng, Yu Jiang, Jinde Yu, Xiaoyun Xu, Zhongxiang Peng, Laju Bu, Ying Zhang, Zheng Tang, Miaomiao Li, Long Ye, Yanhou Geng
Abstract
Three narrow band gap (NBG) acceptors, namely, TTDTC-0F, TTDTC-2F, and TTDTC-4F, were synthesized by introducing a strong electron-donating unit as the central core. The enhanced intramolecular charge transfer endows the three acceptors with high-lying highest occupied molecular orbitals (HOMOs) of ∼−5.20 eV and ultranarrow band gaps (∼1.25 eV). When blended with poly(3-hexylthiophene) (P3HT), all organic solar cells (OSCs) exhibited a broad photoresponse from 300 to ∼1000 nm. Among them, P3HT:TTDTC-4F-based devices achieved the highest efficiency of 7.81% with a prominent Jsc exceeding 22 mA·cm–2. This study demonstrates that the conjugated molecules with high HOMOs can also function as acceptor materials for P3HT-based OSCs, which opens a window to increase PCEs of P3HT-based OSCs in the future to the level of the devices based on the current state-of-the-art polymer donor materials.