Low-Temperature and Ambient Processed All Inorganic CsPbBr₃ Perovskite Solar Cells: Stability Enhancement with AZO as an Electron Transport Layer

All inorganic CsPbBr3-based perovskite solar cells (PSCs) have drawn great attention from researchers because of their high chemical and thermal stability in an open environment. In this work, we successfully replaced the high-temperature deposited mesoporous caping (m-TiO2) electron transport layer (ETL) with a low-temperature deposited aluminum-doped zinc oxide (AZO) ETL and fabricated all inorganic CsPbBr3 PSCs using copper(I) thiocyanate (CuSCN) as a hole transport layer (HTL). The fabricated AZO-based devices exhibited an excellent power conversion efficiency (PCE) of 6.42%, fill factor (FF) of 60.32%, open-circuit voltage (V-OC) of 1.01 V, and short-circuit current density (J(SC)) of 10.38 mA/cm(2), whereas m-TiO2-based devices exhibited PCE of 5.33%, FF of 62.88%, V-OC of 1.02 V, and J(SC) of 8.39 mA/cm(2) under ambient conditions. In terms of stability, the AZO-based device retained 94% of its initial PCE, whereas the m-TiO2-based device retained 69% of its initial PCE after 1000 h of continuous exposure in the ambient atmosphere of relative humidity similar to 81% and room temperature (RT) similar to 27 degrees C without any encapsulation. Therefore, this approach of replacing m-TiO2 with AZO can facilitate the fabrication of efficient and highly stable planar all-inorganic PSCs in an ambient environment. In addition, we represented a cheap encapsulation process for improved stability as an additional advantage.