Oriented Molecular Dipole‐Enabled Modulation of NiO<i>_x</i>/Perovskite Interface for Pb‐Sn Mixed Inorganic Perovskite Solar Cells

Abstract

AbstractNickel oxide (NiOx) is considered as a potential hole transport material in the fabrication of lead‐tin (Pb‐Sn) perovskite solar cells (PSCs) for tandem applications. However, the energy level mismatch and unfavorable redox reactions between Ni≥3+ species and Sn2+ at the NiOx/perovskite interface pose challenges. Herein, high‐performance Pb‐Sn‐based inorganic PSCs are demonstrated by modulating the NiOx/perovskite interface with a multifunctional 4‐aminobenzenesulfonic acid (4‐ABSA) interlayer. The 4‐ABSA interlayer induces the formation of an oriented dipole moment directed from NiOx to perovskite, effectively elevating the valance band maximum of the NiOx film, thus balancing the energy level difference and promoting charge carrier extraction of the device. Moreover, the 4‐ABSA molecules interact with both NiOx and perovskite, suppressing the reaction of highly active Ni≥3+ species with perovskites while regulating perovskite crystallization. This results in perovskite films with reduced defect density and enlarged grains. Consequently, a remarkable device efficiency of 17.4% is obtained, representing the highest reported value for Pb‐Sn‐based inorganic PSCs thus far. Furthermore, the 4‐ABSA interlayer enhances the UV‐radiation and operational stability of the resulting devices, maintaining over 80% and 90% of the initial efficiency after 240 h of UV‐light exposure and 480 h of 1 sun illumination, respectively.