Theoretical investigation of photoelectronic properties in symmetric and asymmetric structures of A–DA′D–A non-fullerene acceptors with diverse central cores

Abstract

We designed six non-fullerene acceptors (BTP-N4F, Qx-4F, L12Se-4F, BP5T-2ThCl, Qx-2ThCl, and Z8-2ThCl) with enhanced photovoltaic performance via optimized structural design and processing. Among them, BTP-N4F/Z8-2ThCl and Qx-4F/Qx-2ThCl differ in terminal groups, while Qx-4F/L12Se-4F and Z8-2ThCl/Qx-2ThCl vary in central cores. Notably, BTP-N4F and BP5T-2ThCl exhibit the most regular molecular architectures and optimal alignment of the HOMO/LUMO energy levels, positioning them as promising candidates for integration with conventional donor materials to facilitate efficient charge transport. L12Se-4F, which possesses the smallest energy bandgap, demonstrates superior light absorption capabilities attributed to its extended conjugation and the electron-donating properties of selenium atoms, rendering it suitable for near-infrared photovoltaic active layers. Additionally, Qx-4F, BP5T-2ThCl, Qx-2ThCl, and Z8-2ThCl show remarkable solvent compatibility and high exciton stability across various solvent environments. The incorporation of –ThCl groups into asymmetric systems, while resulting in variable hole/electron delocalization, contributes to enhanced electron transport and promotes exciton stabilization.