A donor-acceptor integrated polymer for efficient organic solar cells

Here, a donor-acceptor integrated polymer, PQIC, featuring a rigid π-conjugated framework, is reported, in which a Y-type small-molecule acceptor is covalently fused into a polymer donor backbone. PQIC exhibits balanced bipolar charge transport, reduced defect density, and high electroluminescence efficiency. When incorporated as a third component, it facilitates charge percolation, concurrently weakens electron-phonon coupling and lowers defect-state density, thereby alleviating recombination losses. As a result, PQIC-based ternary organic solar cells achieve a power conversion efficiency of 20.81% (third-party certified at 20.60%). In addition to high efficiency, the devices exhibit excellent stability, thick-film tolerance, and scalability, retaining ~85% of their initial efficiency after 2000 hours of maximum power point tracking, delivering 19.11% with a 300-nanometer-thick active layer, and reaching 19.78% for 1-square centimeter devices. These results highlight the potential of PQIC-based ternary systems for advancing organic solar cells.