A Universal Strategy to Utilize Polymeric Semiconductors for Perovskite Solar Cells with Enhanced Efficiency and Longevity

In this contribution, a facile and universal method is successfully reported to fabricate perovskite solar cells (PSCs) with enhanced efficiency and stability. Through dissolving functional conjugated polymers in antisolvent chlorobenzene to treat the spinning CH3NH3PbI3 perovskite film, the resultant devices exhibit significantly enhanced efficiency and longevity simultaneously. In‐depth characterizations demonstrate that thin polymer layer well covers the top surface of perovskite film, resulting in certain surface passivation and morphology modification. More importantly, it is shown that through rational chemical modification, namely molecular fluorination, the air stability and photostability of the perovskite solar cells are remarkably enhanced. Considering the vast selection of conjugated polymer materials and easy functional design, promising new results are expected in further enhancement of device performance. It is believed that the findings provide exciting insights into the role of conjugated polymer in improving the current perovskite‐based solar cells. By dissolving conjugated polymer in antisolvent, the antisolvent is updated to antisolution in perovskite solar cell fabrication. Benefiting from a favorable arrangement of polymer layers, the device containing polymer exhibits improved photovoltaic efficiency (18.7%) and long‐term stability. More importantly, it is shown that molecular fluorination of these functional polymers enhances device performance further.