Effects of End‐Group Modifications of A2‐A1‐D‐A1‐A2 Type of Four‐Bladed Propeller‐Like Non‐Fullerene Acceptors on Optoelectronic Properties: A Computational Analysis

ABSTRACT Small‐molecule non‐fullerene acceptors (SM‐NFAs) featuring a three‐dimensional and four‐bladed propeller‐like structure have gained attention due to their unique molecular framework as a guest component in ternary organic solar cells (TOSCs). However, there is currently a scarcity of theoretical research into the photovoltaic properties of these SM‐NFAs. This gap is especially pronounced when it comes to comprehending how modifications to their end groups (EGs) influence their electronic structures. In this work, SF‐BTA1, SF‐BTA2, and SF‐BTA3 SM‐NFAs are selected since they have been experimentally synthesized and have different impacts on the performance of TOSCs. Using density functional theory (DFT) and time‐dependent DFT (TDDFT), we have computed and analyzed their ground state and excited state properties, including molecular planarity, electrostatic potential maps and their corresponding fluctuations, dipole moments, frontier molecular orbitals, electron–hole distributions, UV–Vis absorption spectra, singlet‐triplet energy gap difference (∆E ST ), and exciton binding energy, as well as the open‐circuit voltage of OSCs based on these four‐bladed propeller‐like molecules. The theoretical results align well with experimental data. Furthermore, as a guest acceptor, SF‐BTA1 exhibits the smallest electrostatic potential fluctuations and singlet‐triplet energy gap (∆E ST ). This implies that these two factors could play crucial roles in evaluating whether a four‐bladed propeller‐like molecule is suitable to serve as an effective guest acceptor. Our results not only unveil the underlying mechanism about the roles of these NFAs in TOSCs but also provide valuable insights for the further design and optimization of highly efficient TOSCs.