Harnessing Surface Dipole for CsPbI3 Perovskite Solar Cells with Poly(3‐hexylthiophene)

The efficient functioning of perovskite solar cells largely depends on the interaction between perovskite halide materials and the hole‐transport layer poly(3‐hexylthiophene) (P3HT). However, a high rate of nonradiative recombination often hampers this interaction, leading to poor performance of the solar cells. We have developed a technique to modify the interface using a long‐chain alkyl halide molecule called n‐hexyl trimethylammonium bromide to address this issue. This modification technique significantly improves hole extraction, leading to an impressive open‐circuit voltage of 1.14 V and a power conversion efficiency of 15.8% for inorganic perovskite CsPbI3 with P3HT as a dopant‐free hole‐transport layer. This breakthrough can pave the way for developing more efficient and sustainable solar cells.