Designing and Screening High‐Performance Non‐Fullerene Acceptors: A Theoretical Exploration of Modified Y6

Recently, the application of the non‐fullerene acceptor (NFA) Y6 and its derivatives has increased the power conversion efficiencies (PCEs) of organic solar cells (OSCs) up to 18.22%. It has opened up a new revolutionary direction of the molecular design of high‐performance NFAs. Despite the recent exciting experimental progress of Y6‐based OSCs, studies of molecular modifications of Y6, which may be the most effective way to improve the PCE of OSCs, are still few. Herein, a series of modified Y6 molecules is systematically designed and modeled. Their physical and optical properties are predicted with reliable density functional theory (DFT) and time‐dependent DFT calculations. The dipole moments, frontier molecular orbital energies, UV–vis absorption spectra, singlet–triplet energy gaps, exciton binding energies, charge transfer rate constants at the donor–acceptor interface, and electron mobility are computed to comprehensively analyze the potential of these Y6 derivatives. The results show that proper extension of the backbone by inserting thiophene rings with a single‐bond connection is conducive to designing highly efficient NFAs. The most striking finding here is that one (named BTPTT‐4F‐2T) of the screened Y6 derivatives is superior to prototype Y6 in all aspects and may be the next star high‐performance NFA.