Plasma-Enhanced Grain Growth and Non-Radiative Recombination Mitigation in CsSnBr₃ Perovskite Films for High-Performance, Lead-Free Photodetectors

Tin-based halide perovskites represent a highly promising and eco-friendly alternative to lead-based materials with significant potential for optoelectronic applications. However, their advancement is hampered by challenges such as poor film crystallinity and unintended self-doping. Herein, this work reports the fabrication of high-quality CsSnBr₃ perovskite films by plasma-assisted chemical vapor deposition (PACVD), which improves the film quality. The precise control of the ammonia plasma not only promotes grain growth and reduces grain boundaries, but also eliminates defect states in the film, mitigates oxidation of Sn²⁺, suppresses sub-bandgap absorption, and reduces non-radiative recombination. Consequently, the photodetectors deliver exceptional performance, including a responsivity of 11.2 A W^-1, a detectivity of 2.5 × 10¹¹ Jones, and an ultrafast response time of 1/3.3 ms. Notably, certain key metrics, including detectivity (D*) and response time, significantly surpass those of all previously reported photoconductor-type Sn-based perovskite photodetectors. The results offer not only a novel strategy for enhancing the quality and optoelectronic performance of CsSnBr₃ films but also a scalable platform for the development of high-performance, lead-free perovskite materials and devices. The new knowledge opens new possibilities for the design and fabrication of sustainable materials for advanced optoelectronic applications.