A 0D/3D Heterostructured All-Inorganic Halide Perovskite Solar Cell with High Performance and Enhanced Phase Stability

Although organic-inorganic hybrid perovskite solar cells (PVSCs) have achieved dramatic improvement in device efficiency, their long-term stability remains a major concern prior to commercialization. To address this issue, extensive research efforts are dedicated to exploiting all-inorganic PVSCs by using cesium (Cs)-based perovskite materials, such as alpha-CsPbI3. However, the black-phase CsPbI3 (cubic alpha-CsPbI3 and orthorhombic gamma-CsPbI3 phases) is not stable at room temperature, and it tends to convert to the nonperovskite delta-CsPbI3 phase. Here, a simple yet effective approach is described to prepare stable black-phase CsPbI3 by forming a heterostructure comprising 0D Cs4PbI6 and gamma-CsPbI3 through tuning the stoichiometry of the precursors between CsI and PbI. Such heterostructure is manifested to enable the realization of a stable all-inorganic PVSC with a high power conversion efficiency of 16.39%. This work provides a new perspective for developing high-performance and stable all-inorganic PVSCs.