A π-conjugated polymer as dopant-free hole transporting material for perovskite solar cells with efficiency approaching 19%

Perovskite solar cells (PSCs) have attracted considerable attention due to their outstanding advantages, such as cost-effective, easy fabrication, and high efficiency. Herein, we designed and synthesized siloxane-functionalized π-conjugated polymer Nap-SiBTAz2. The rational structural including benzodithiophene, difluorobenzotriazol unit and alkyl-siloxane enable excellent hole mobility and good solubility. Interestingly, dopant-free Nap-SiBTz2 as hole transporting material (HTM) in PSC exhibited impressive power conversion efficiency of 19.0% with open-circuit-voltage 1.14 V, short-circuit current density 23.6 mA cm−2, and fill factor 70.7%. These results proved that Nap-SiBTz2 is a promising HTM candidate for PSCs, while providing a rational method to design dopant-free HTM for high-efficiency PSCs.