Spray Pyrolysis Deposition of CuCrO2 Films as Promising Inorganic Hole Transport Layers for Highly Efficient Perovskite Solar Cells

Abstract

Recently, CuCrO2 films have been successfully introduced as effective hole‐transporting materials in perovskite solar cells (PSCs). However, the long reaction time (≈50–60 h) at the high temperature of hydrothermal synthesis and the complexity of conversion from nanoparticles to uniform films hinder the application of CuCrO2 nanoparticles in PSCs. Herein, a simple, low‐cost, and highly reproducible method for the spray pyrolysis deposition (SPD) of Cu‐deficient CuCrO2 films is reported. The resulting CuCrO2 films exhibit advantages in terms of transparency, roughness, and electrical properties compared to their extensively studied NiO x counterparts. Meanwhile, the deep‐lying valence‐band‐maximum of CuCrO2 films matches very well with that of perovskite materials, minimizing the charge‐extraction barrier. As a result, the excellent electrical properties and energetically favorable energy‐level alignment of the CuCrO2 film allow efficient charge transport from the perovskite layer to the hole transport layer (HTL). Consequently, the optimized CuCrO2‐based device delivers an outstanding power conversion efficiency of 18.86% versus 16.80% for NiO x ‐based devices. This work demonstrates the validity of a CuCrO2 film derived from the SPD method as an HTL for highly efficient PSCs.