Achieving 19.5% Efficiency via Modulating Electronic Properties of Peripheral Aryl‐Substituted Small‐Molecule Acceptors

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-11, Vol.20 (47), p.e2405476-n/a
• Main Authors: Xu, Tongle, Ran, Guangliu, Luo, Zhenghui, Chen, Zhanxiang, Lv, Jie, Zhang, Guangye, Hu, Hanlin, Zhang, Wenkai, Yang, Chuluo
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Density functional theory; Electronic properties; Energy conversion efficiency; organic solar cell; peripheral aryl substitution; power conversion efficiency; Quinoxalines; Substitutes; ternary device
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202405476

The advancement of acceptors plays a pivotal role in determining photovoltaic performance. While previous efforts have focused on optimizing acceptor–donor–acceptor1–donor–acceptor (A–DA1–D–A)‐typed acceptors by adjusting side chains, end groups, and conjugated extension of the electron‐deficient central A1 unit, the systematic exploration of the impact of peripheral aryl substitutions, particularly with different electron groups, on the A1 unit and its influence on device performance is still lacking. In this study, three novel acceptors – QxTh, QxPh, and QxPy – with distinct substitutions on the quinoxaline (Qx) are designed and synthesized. Density functional theory (DFT) analyses reveal that QxPh, featuring a phenyl‐substituted Qx, exhibits the smallest molecular binding energies and a tightest π···π stacking distance. Consequently, the PM6:QxPh device demonstrates a better power conversion efficiency (PCE) of 17.1% compared to the blends incorporating QxTh (16.4%) and QxPy (15.7%). This enhancement is primarily attributed to suppressed charge recombination, improved charge extraction, and more favorable molecular stacking and morphology. Importantly, introducing QxPh as a guest acceptor into the PM6:BTP‐eC9 binary system yields an outstanding PCE of 19.5%, indicating the substantial potential of QxPh in advancing ternary device performance. The work provides deep insights into the expansion of high‐performance organic photovoltaic materials through peripheral aryl substitution strategy. The authors develop three acceptors with different electronic property substitutions on the quinoxaline unit, namely QxTh, QxPh, and QxPy. Notably, the binary organic solar cell (OSC) based on PM6:QxPh yields a efficiency of 17.1%. Moreover, QxPh demonstrates great promise as a guest acceptor in realizing high‐performance ternary OSCs, showcasing a remarkable efficiency of 19.5%.