Replacement of conventional organic cations by thermally stable inorganic cations in perovskite solar cells (PSCs) is one of the promising approaches to make thermally stable photovoltaics. However, conventional spin-coating and solvent-engineering processes in a controlled inert atmosphere hamper the upscaling. In this study, we demonstrated a dynamic hot-air (DHA) casting process to control the morphology and stability of all-inorganic PSCs which is processed under ambient conditions and free from conventional harmful antisolvents. Furthermore, CsPbI2Br perovskite was doped with barium (Ba2+) alkaline earth metal cations (BaI2:CsPbI2Br). This DHA method facilitates the formation of uniform grain and controlled crystallization that makes stable all-inorganic PSCs which enables an intact black α-phase under ambient conditions. The DHA-processed BaI2:CsPbI2Br perovskite photovoltaics shows the champion power conversion efficiency (PCE) of 14.85% (reverse scan) for a small exposure area of 0.09 cm2 and 13.78% for a large area of 1 × 1 cm2 with excellent reproducibility. Interestingly, the hot-air-processed devices retain >92% of the initial efficiency after 300 h. This DHA method facilitates a wide processing window for upscaling the all-inorganic perovskite photovoltaics.
Keywords: All-inorganic perovskites; CsPbIBr perovskites; barium incorporation; hot-air method; stability.