Wafer‐Scale Room‐Temperature Processing of Lead‐Free Perovskites for Optoelectronic Applications

Scalable and sustainable synthesis methods for high-performance optoelectronic materials are essential to the advancement of next-generation optoelectronic and photonic technologies. Metal halide perovskites have rapidly gained prominence as versatile semiconductors across applications ranging from photovoltaics to lighting and sensing. However, their commercial deployment is hindered by the pervasive use of toxic lead-based compositions and the lack of environmentally friendly, industry-compatible fabrication processes. While lead-free alternatives based on group IVA elements such as tin have shown encouraging optoelectronic properties, their widespread adoption is limited by their chemical instability under ambient conditions. Antimony-based perovskite analogues are an emerging robust alternative, offering enhanced environmental stability, yet their synthesis has thus far depended on low-throughput single-crystal growth or solution processing routes that involve hazardous solvents and offer limited control over film structure and uniformity. Here, we demonstrate the first wafer-scale, room-temperature synthesis of high-quality lead-free Cs₃Sb₂Br₉ and Cs₃Sb₂I₉ thin films using radio frequency magnetron sputtering, a scalable, solvent-free deposition technique extensively employed in semiconductor and display manufacturing for the large-area deposition of metals, transparent conductive oxides and dielectric layers. The resulting films exhibit single-phase crystallinity, tuneable optical bandgap ranging from 2.17 to 2.71 eV, and are well suited for UV-visible optoelectronics. Integrated into planar photodetectors, these materials achieve a photoresponsivity of 3.3 A/W, a bandwidth of 11 kHz, a linear dynamic range of 165 dB, and a detectivity of 1.7 × 10¹⁵ Jones, surpassing many state-of-the-art devices. These findings establish magnetron sputtering as a powerful platform for the scalable fabrication of lead-free perovskite optoelectronics and lay the foundation for their application beyond photovoltaics.