Journal Article

Fully non-fused electron acceptor solar cells with 18% efficiency via a synergistic peripheral substituent strategy

He, Zhicai, Yang, Mingqun, Yuan, Xiyue, Huang, Fei, Cao, Yong, Zhang, Wei, Wang, Yeye, Ma, Zaifei, Chen, Zhili, Zhong, Jianbin, Zhao, Feixiang, Duan, Chunhui, Wei, Wenkui, Liu, Zhitian

2025

Overview

Toward commercialization of organic solar cells (OSCs), photoactive materials that enable high efficiency yet possess low cost should be developed. Fully non-fused ring electron acceptors (FNEAs) that extend the conjugated skeleton with carbon–carbon (C–C) single bonds solely have lower synthetic costs than their fused-ring counterparts. However, the power conversion efficiencies (PCEs) of FNEAs are lagging due to low acceptor crystallinity and difficulty in the formation of fibrillary bi-continuous interpenetrating network morphology. Herein, we report four FNEAs (NEH-4F, EEH-4F, NBO-4F, and EBO-4F) through rational design of peripheral substituents. Specifically, the encapsulated central core guarantees the planarity of the conjugated skeleton and improves acceptor crystallinity, while the lengthened outer side chains modulate the molecular stacking and regulate the thermodynamic compatibility between the FNEAs and the polymer donor PTTz. Therefore, nanoscale phase separation morphology with bi-continuous interpenetrating fibril network structures was found in the blend of PTTz:EBO-4F, which promotes exciton diffusion and charge transport in solar cells. A record-breaking PCE of 18.04% is thus obtained, which greatly reduces the efficiency gap between FNEAs and fused-ring electron acceptors. These results demonstrate the promising prospect of fabricating high-efficiency OSCs from low-cost FNEAs through rational molecular design. The performance of devices based on fully non-fused ring electron acceptors has been limited due to the low acceptor crystallinity. Here, authors report these acceptors with peripheral substituents that guarantee the planarity of the skeleton, achieving efficiency of 18.04% in organic solar cells.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 639/301/299/946 / 639/4077/909/4101/4096/946 / Carbon / Charge transport / Chemical bonds / Commercialization / Crystallinity / Crystallization / Energy conversion efficiency / Excitons / Humanities and Social Sciences / Interpenetrating networks / Low cost / Molecular chains / Morphology / multidisciplinary / NMR / Nuclear magnetic resonance / Phase separation / Photovoltaic cells / Polymers / Science / Science (multidisciplinary) / Solar cells