Facilely full-end-capping engineering promotes high-performance organic solar cells with simultaneously improved efficiency and stability

Main-chain construction and side-chain modification are general strategies to design polymer donors for organic solar cell (OSCs), but they always suffer from deliberate molecular design and tedious synthesis. Here, we employ full-end-capping engineering, a facile and versatile strategy to boost both efficiency and stability for non-fullerene OSCs. A series of full-end-capped polymer donors are obtained by a simple end-capping reaction right after the polymerization in one-pot. It is found that the end-capping groups not only completely remove the unreacted terminal defects in the polymer chains, but also well-manipulate the molecular orientation, film-forming process and resulting morphology, optimize the charge dynamics, and reduce non-radiative energy loss. The device with full-end-capped PM6-T:Y6-based obtains an impressive efficiency of 17.11%, showing all-over improved device parameters and long-term stability than unend-capped PM6:Y6-based device (15.96%). Notably, PM6-T:BTP-eC9-based device reaches a efficacy of 18.45%, among the highest performance of BTP-eC9-based devices.