Inorganic metal halide (IMH) perovskites have garnered significant attention in the field of perovskite photovoltaics due to their exceptional thermal stability compared to organic-inorganic hybrid counterparts. Since their initial report in 2015, IMH perovskites have achieved power-conversion efficiencies (PCEs) exceeding 20% [1]. However, the limited solubility of inorganic compounds in conventional solvents poses challenges for uniform film deposition and crystallization using lab-scale solution-processing techniques. To address these issues, researchers have explored alternative solvent systems and processing techniques, including crystallization regulation, composition engineering, interface engineering, and novel charge transport layers [2]. Thermal evaporation (TE), a well-established method in the semiconductor industry, presents a promising approach for fabricating IMH perovskite films, particularly cesium-based compositions, by circumventing the solubility limitations of wet-chemistry approaches. TE is also suitable for the fabrication of oxygen-sensitive or metastable perovskites such as cesium lead mixed halide (CsPbI₂Br). In this study, we investigated the effect of substrate temperature on characteristics of stoichiometrically balanced CsPbI₂Br thin films fabricated by co-evaporation of CsBr and PbI₂ precursors under high vacuum conditions. While previous reports on thermally evaporated CsPbI₂Br emphasized the need for high post-annealing temperatures (>260 °C) [2, 3] or utilizing multiple deposition sources [4] to obtain good film morphology, we demonstrated the importance of applying substrate temperature during film fabrication, coupled with a mild post-annealing temperature at 150 °C. The substrate heating during deposition resulted in films with improved crystallinity and phase stability. Additionally, passivation of the perovskite layer with phenethylammonium chloride (PEACl) and the integration of NiO_x/MeO-2PACz as a hybrid hole transport layer (HTL), resulted in a PCEs of 13.21% in p-i-n PSCs based on vacuum-deposited CsPbI₂Br films with a bandgap of 1.9 eV. Notably, encapsulated devices maintained 80% of their initial efficiency under 1-sun illumination for 450 hours. This study underscores the most promising approaches for optimizing CsPbI₂Br perovskite vacuum deposition and enhancing the performance of p-i-n solar cell architectures.