Hole‐Transporting Molecules with Tetrabenzo[a,c,g,i]carbazole Core for Highly Efficient Perovskite Solar Cells

Hole‐transporting materials (HTMs) are the key component of perovskite solar cells (PSCs) for the role of extracting photogenerated holes, as well as the charge transporting between perovskite layer and metal electrode. Herein, with the aim to enhance the hole mobility by compact molecular packing, the modification of HTMs focuses on the extension of conjugated cores from the commonly used carbazole (Cz) to tetrabenzo[ a , c , g , i ]carbazole (TBC). Because of the closely cofacial stacking mode of the TBC core with an X‐type symmetric structure, the resultant TBC‐2,7,11,16‐ tetra ‐diphenylamine (TD) can achieve a hole mobility of 6.6 × 10 −4 cm 2 V −1 s −1 and the corresponding conversion efficiency of 20.52%, higher than that of the analogue Cz‐TD (18.34%).