New Medium-Bandgap\nNonfused Ring Guest Acceptor with\na Higher-Lying LUMO Level Enables High-Performance Ternary Organic\nSolar Cells

Abstract

Adding another constituent into a binary system, known\nas a ternary\nstrategy, represents a simple and effective approach to boosting the\npower conversion efficiency (PCE) of organic solar cells (OSCs). Herein,\nwe have prepared a new nonfused ring small-molecule acceptor with\na medium bandgap, named DFTQA-2FIC, which possesses a high-lying lowest\nunoccupied molecular orbital energy level and a strong intramolecular\ncharge-transfer effect. We elaborately utilized it as a third component\nin a typical PM6:Y6 blend to obtain high-performance ternary OSCs.\nThe resulting ternary blend film exhibited superior and balanced hole/electron\nmobility, enhanced favorable aggregation morphology, and reduced charge\ncarrier recombination. Consequently, an optimized ternary OSC presented\na distinctly increased PCE of 17.29%, accompanied by synchronous enhancements\nin crucial parameters, representing a 7.46% improvement over the binary\nOSC based on PM6:Y6 with a PCE of 16.09%. This study highlights that\nincorporating DFTQA-2FIC as a third component in a binary system is\nsuitable for optimizing photovoltaic performance.