Although the field of polymer solar cell has seen much progress in device performance in the past few years,several limitations are holding back its further development.For instance,current high-efficiency(>9.0%)cells are restricted to material combinations that are based on limited donor polymers and only one specific fullerene acceptor.Here we report the achievement of high-performance(efficiencies up to 10.8%,fill factors up to 77%)thick-film polymer solar cells for multiple polymer:fullerene combinations via the formation of a near ideal polymer:fullerene morphology that contains highly crystalline yet reasonably small polymer domains.This morphology is controlled by the temperature-dependent aggregation behaviour of the donor polymers and is insensitive to the choice of fullerenes.The uncovered aggregation and design rules yield three high-efficiency(>10%)donor polymers and will allow further synthetic advances and matching of both the polymer and fullerene materials,potentially leading to significantly improved performance and increased design flexibility.