Perovskite solar cells (PSCs) have shown excellent promise in achieving high power conversion efficiencies and thermal stability with state-of-the-art material engineering and device optimization. The control of the thickness of the perovskite absorber layer and its defect density allows for a balance to be achieved between optimal light absorption and charge-carrier recombination. This theoretical study introduces a solar cell design featuring a CH₃BaSnI₃-based perovskite absorber layer combined with a zinc oxide (ZnO) hole-transport layer. The newly developed device demonstrated exceptional performance metrics, including high power conversion efficiency (PCE) and fill factor (FF), robust temperature stability, and environmental friendliness, all achieved at a low cost. Using 1D SCAPS simulations and analysis, the innovative perovskite solar cell (PSC) achieved a PCE of 22.24% and FF of 83% at 45°C, with a quantum efficiency exceeding 85% across the visible spectrum. The introduction of GO and mesoporous carbon does not affect the performance of the PSC at high temperatures, ranging from 85°C to 95°C. Replacing toxic Pb-based materials in the proposed device with environmentally friendly components, such as ZnO, GO, and mesoporous carbon, reduced the environmental impact and significantly decreased the production cost. Consequently, this design for PSC holds excellent prospects for large-scale solar energy applications. Highlights