Energy Disorder Suppression, Charge Transport Channel Establishment by Integrating Four-Arm Donor Molecule for High-Performance Organic Solar Cells

Abstract

Organic solar cells (OSCs) typically exhibit large energy disorders due to the complicated blend morphology, which is one of the important factors in limiting the improvement of power conversion efficiencies (PCEs). Herein, two new cross-shaped donor molecules, BTCl-4R and BT-4R, featured with central benzodithiophene (BDT) cores flanked with four π-bridges and hexylrhodanine end groups are developed, which are introduced into OSCs as a third component to optimize the packing behaviors and reduce energy disorder. By blending with the classical PM6:L8-BO system, the outstanding PCE of 20.03% with a low energy disorder of 32 meV is achieved, as higher packing order lowers the trap density and inter-connected morphology facilitates the establishment of more charge transport channels. This study demonstrates the significant potential of multi-arm donor molecules in constructing high-performance OSCs.