Single‐Junction Organic Solar Cells with 19.17% Efficiency Enabled by Introducing One Asymmetric Guest Acceptor

• Published in: Advanced materials (Weinheim) Vol. 34; no. 26; pp. e2110147 - n/a
• Main Authors: Sun, Rui, Wu, Yao, Yang, Xinrong, Gao, Yuan, Chen, Zeng, Li, Kai, Qiao, Jiawei, Wang, Tao, Guo, Jing, Liu, Chao, Hao, Xiaotao, Zhu, Haiming, Min, Jie
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-07-2022
• Subjects: Absorption spectra; Asymmetry; Diffusion length; Electric potential; electron acceptors; Energy conversion efficiency; Excitons; long‐term stability; Materials science; nonradiative recombination; organic photovoltaic cells; Photoluminescence; Photovoltaic cells; Solar cells; ternary strategy; Voltage; organic photovoltaic cells; long-term stability; nonradiative recombination; ternary strategy; electron acceptors
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202110147

The ternary strategy has been widely identified as an effective approach to obtain high‐efficiency organic solar cells (OSCs). However, for most ternary OSCs, the nonradiative voltage loss lies between those of the two binary devices, which limits further efficiency improvements. Herein, an asymmetric guest acceptor BTP‐2F2Cl is designed and incorporated into a PM1:L8‐BO host blend. Compared with the L8‐BO neat film, the L8‐BO:BTP‐2F2Cl blend film shows higher photoluminescence quantum yield and larger exciton diffusion length. Introducing BTP‐2F2Cl into the host blend extends its absorption spectrum, improves the molecular packing of host materials, and suppresses the nonradiative charge recombination of the ternary OSCs. Consequently, the power conversion efficiency is improved up to 19.17% (certified value 18.7%), which represents the highest efficiency value reported for single‐junction OSCs so far. The results show that improving the exciton behaviors is a promising approach to reducing the nonradiative voltage loss and realizing high‐performance OSCs.
A new ternary system is developed by introducing an asymmetric electron acceptor BTP‐2F2Cl into the PM1:L8‐BO host system. The ternary system exhibits a record‐high efficiency of 19.17% and demonstrates better long‐term stability compared to the host system.