Self‐doped conjugated polymers with electron‐deficient quinone units for enhanced electron transport in highly efficient organic solar cells

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AbstractOrganic solar cells (OSCs) have attracted significant attention as a burgeoning flexible technology, owing to their advanced power conversion efficiencies. Moreover, interface materials play a crucial role in optimizing energy level alignment between the active layer and electrodes, thereby enhancing carrier extraction within the device and improving efficiency. However, current methodologies for fabricating electron‐transport materials with superior mobility are still limited compared with those for hole‐transport materials. In this study, a benzodifurandione (BFDO)‐derived building block with quinone resonance property and strong electron‐withdrawing capability was synthesized. Two conjugated polymers, namely PBFDO‐F6N and PBFDO‐F6N‐Br, were prepared, both of which exhibited good electron mobility and exceptional interface modification capabilities. A comprehensive investigation of the interaction between the interface layer and the active layer revealed that PBFDO‐F6N induced doping at the acceptor interface. Additionally, the high mobility of PBFDO‐F6N facilitated efficient carrier extraction at the interface. Consequently, the application of PBFDO‐F6N as the cathode interface layer for PM6:BTP‐eC9‐based OSC devices resulted in a remarkable efficiency of 18.11%. Moreover, the device efficiency remained at ∼96% even at a PBFDO‐F6N interface thickness of 50 nm, demonstrating the great potential of this material for large‐scale device preparation.