Pyrene‐Based Dopant‐Free Hole‐Transport Polymers with Fluorine‐Induced Favorable Molecular Stacking Enable Efficient Perovskite Solar Cells

A new class of polymeric hole-transport materials (HTMs) are explored by inserting a two-dimensionally conjugated fluoro-substituted pyrene into thiophene and selenophene chains. The broad plane “Lewis soft” selenium atoms not only enhance the π–π stacking HTM molecules greatly but also render strong interaction with perovskite surface, leading to an efficient charge transport/transfer in both layer perovskite/HTM interface. Note that fluorine substitution adjacent boosts HTMs towards more favorable face-on orientation, further facilitating transport. As result, solar cells (PSCs) employing PE10 as dopant-free afford excellent efficiency 22.3 % dramatically enhanced device longevity, qualifying it among best PSCs based on HTMs.