Combinatorial design of copolymer donor materials for bulk heterojunction solar cells.

Seeking π-conjugated polymers with targeted optical band gaps is not only a grand scientific challenge but also in great practical need for systematically improving the performance of organic optoelectronic devices. This work presents a generic combinatorial band-gap design strategy over 780 different copolymer donor materials for bulk heterojunction solar cell applications. Predicted optical band gaps effectively cover the entire solar spectrum from infrared, to visible, to ultraviolet. Combined with empirical arguments widely acknowledged in the literature, the optimal copolymer structures are identified for both single and tandem cells with the optimal power conversion efficiencies.