Synergistic Enhancement of <i>V</i>_OC in Tin Halide Perovskite Solar Cells Through Growth Annealing Temperature Optimization via Mitigating Bulk Defects and Nonradiative Recombination

Large organic cation mixed tin-halide perovskites (LOTHP) have emerged as a promising nontoxic alternative to lead-halide counterparts, offering improved power conversion efficiency (PCE) and stability. The influence of various growth-annealing temperatures (ga-T) on these materials, typically processed above 70 °C, has been poorly understood. This study explores ga-T ranging from 40 to 120 °C, revealing that higher ga-T significantly enhances perovskite film crystallinity, increases crystallite size, and reduces both nonradiative recombination and bulk defect density. Consequently, these outcomes lead to a substantial boost in photovoltaic performance, evidenced by a 130% increase in open-circuit voltage (VOC) and a 33% rise in current density (JSC) at ga-T ranging from 40 to 100 °C. Computational simulations further validate these experimental findings, exploring the structural changes, defect density variation, and energy level shifts in LOTHP. These combined investigations elucidate the underlying driving mechanisms behind reduced nonradiative losses and improved energy level alignment with transport layers, significantly enhancing the VOC. These findings underscore the significance of ga-T in optimizing the electronic quality of tin-halide perovskite films for a superior solar cell performance. Understanding these temperature-dependent effects is crucial for advancing the development of efficient and stable large area tin perovskite-based photovoltaics.