Random Terpolymer Enabling High‐Efficiency Organic Solar Cells Processed by Nonhalogenated Solvent with a Low Nonradiative Energy Loss

Abstract Three terpolymer donors (PL1, PL2, and PL3) employing repeating units of two popular photovoltaic polymers PM6 and D18 are synthesized by random copolymerization. The terpolymers can reduce the regio‐regularity of the polymer backbones and endow them with much‐enhanced solubility in nonhalogenated solvents such as o ‐xylene. Furthermore, along with the appearance of temperature‐dependent aggregation behavior, indicating the adaptability for fabricating organic solar cells (OSCs) by eco‐friendly solvent processing. Among them, PL1‐based OSCs display higher and more balanced hole and electron mobilities, longer charge separation exciton lifetime, and better exciton dissociation and charge collection capabilities than the parent polymers (PM6 and D18) based ones. A power conversion efficiency of 18.14% with a very low energy loss is achieved based on terpolymer PL1, which is much higher than that of PM6 (15.16%) and D18 (16.18%). The result provides an effective way to realize high‐performance nonhalogenated processing polymer donor materials.