All Inorganic Layer Perovskite Solar Cells Based on Oxide/Halide/Oxide Architecture

Inorganic CsPbI₂Br perovskite has outstanding thermal stability and substantial potential for semi-transparent solar cells. However, Cesium-based perovskite solar cells (PSCs) exhibit phase instability due to the perovskite film's moisture penetration. Therefore, 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) which has been commonly used as hole transporting layers (HTLs) in high-performance PSCs is not suitable for CsPbI₂Br-based PSCs. Herein, we report all inorganic layer PSCs based on oxide/halide/oxide architecture for the high stability and performance of PSCs. We introduced nickel oxide (NiOx) nanoparticles overlayer on the perovskite layer as HTLs. As a result, the all-inorganic layer device shows an improved thermal stability and power conversion efficiency (PCE) of 16.67%. In addition, we fabricated the semi-transparent devices by sputtering the tin-doped indium oxide (ITO) as an electrode, which achieved an average visible transmittance higher than 20%. All inorganic layer PSCs with oxide/halide/oxide also showed superior storage stability without encapsulation under 10% relative humidity, retaining over 85% of initial PCE for 1000 h. We believe that this architecture with n-type oxide/inorganic perovskite/p-type oxide represents a cornerstone for the high stability of PSCs.