Suppressing Oxidation at Perovskite-NiO x Interface for Efficient and Stable Tin Perovskite Solar Cells.

Inorganic nickel oxide (NiO x ) is an ideal hole transport material (HTM) for the fabrication of high-efficiency, stable, and large-area perovskite photovoltaic devices because of its low cost, stability, and ease of solution processing; However, it delivers low power conversion efficiency (PCE) in tin perovskite solar cells (TPSCs) compared to other organic HTMs. Here, we identify the origin of hole transport barriers at the perovskite-NiO x interface and develop a self-assembled monolayer (SAM) interface modification, through introducing (4-(7H-dibenzo[c,g]carbazol-7-yl)ethyl)phosphonic acid (2PADBC) into the perovskite-NiO x interface. The 2PADBC anchors undercoordinated Ni cations through phosphonic acid groups, suppressing the reaction of highly active Ni ≥3+ defects with perovskites, while increasing the electron density and oxidation activation energy of Sn at the perovskite interface, reducing the interface non-radiative recombination caused by tetravalent Sn defects. The devices deliver significantly increased open-circuit voltage from 0.712 V to 0.825 V, boosting the PCE to 14.19% for the small-area device and 12.05% for the large-area (1 cm 2 ) device. In addition, the 2PADBC modification enhances the operational stability of NiO x -based TPSCs, maintaining more than 93% of their initial efficiency after 1000 hours. This article is protected by copyright. All rights reserved.