Perovskite solar cells (PSCs), advancing solar technology with remarkable photoconversion efficiency (PCE) and stability, typically use hybrid organic-inorganic lead halide perovskites. However, concerns remain about the organic component's impact on degradation. Transitioning to all-inorganic cesium perovskites is an alternative route to tackle the long-term stability challenges in PSCs. Within inorganic perovskites, CsPbI₃ suffers from polymorphism ranging from the photoactive α-phase to the inactive δ-phase. In contrast, CsPbBr₃ perovskites offer robust thermal, humidity, light stability and do not suffer from polymorphism. With a Shockley-Queisser single-junction limit of ~ 16% and a wide bandgap of 2.3eV, it is attractive for semi-transparent, building-integrated photovoltaics, and multi-junction applications. Many CsPbBr₃ works are based on solution-processing using conventional spin coating technique, limiting uniformity over large areas. Also, dissolving the precursors in solution, which frequently comes with toxicity concerns, can be challenging. Alternatively, thermal evaporation offers a solvent-free, industry-compatible fabrication method, enabling precise thickness control, conformal and uniform coverage over large substrates. Here, we fabricate a solvent-free CsPbBr₃ PSC via dual-source sequential evaporation. CsPbBr₃ films, deposited on compact SnO₂ electron transport layer, are pinhole-free and exhibit phase purity with reduced defects. Thin film annealing studies using X-ray diffraction, conducted alongside device investigations, revealed a decrease in phase transition temperature from 300°C to 250°C. Finally, the fabricated device results in a PCE of 5.6% with an open-circuit voltage of 1.4V. An all-inorganic PSC with a vacuum-processed absorber layer is demonstrated to achieve a phase-pure, compact film of the desired thickness, paving the way for exploring CsPbBr₃ active layer.

Evaporated Perovskite Solar Cells, All-inorganic Perovskite Solar Cells, Wide Bandgap Photovoltaics, Semi-transparent and Building-integrated PV