N-alkyl chain modification in dithienobenzotriazole unit enabled efficient polymer donor for high-performance non-fullerene solar cells

The facile side-chain engineering of donors can significantly promote the PCE of the BHJ-PSC devices from 9.17% to 15.31% because shortening alkyl chains leads to higher crystallinity and preferred face-on stacking, which facilitates photogenerated-electrons transmission and collection.