Sequentially Fluorinated Polythiophene Donors for High-Performance Organic Solar Cells with 16.4 Efficiency

摘要

Polythiophenes (PTs) have attracted considerable interest for application inorganic solar cells (OSCs) owing to their simple molecular structures andlow-cost synthesis. However, the power conversion efficiencies (PCEs) ofPT-based OSCs are lower than those of state-of-the-art OSCs. Herein, thedevelopment of two sequentially fluorinated PT donors (PT-2F and PT-4F) isreported for realizing highly efficient OSCs. PT-2F and PT-4F are designedto contain two and four fluorine atoms, respectively, per repeating unit todecrease their highest occupied molecular orbital energy levels and increasethe open-circuit voltages of the OSCs. Importantly, the PT-4F polymers exhibithigh backbone rigidity and the desired temperature-dependent aggregationbehavior, affording well-developed crystalline structures in thin films forefficient charge transport. These beneficial features promote the constructionof an optimal blend morphology of PT-4F:small-molecule acceptor with a suitableenergy offset and low energetic disorder. Thus, the PT-4F-based binaryand ternary OSCs achieve high PCEs of 15.6% and 16.4%, respectively.