Low-Temperature Fabrication of Stable Black-Phase CsPbI₃ Perovskite Flexible Photodetectors Toward Wearable Health Monitoring

Low-temperature fabrication of black-phase CsPbI₃ perovskite films is first demonstrated by using diphenylphosphinic chloride additive under 30–50 °C, arising from the steric effect and chloride insertion engineering. Large-area high-quality all-inorganic perovskite films with fewer defects enhanced crystallographic orientation, and excellent environmental stability is fabricated. The record performances are demonstrated for flexible wearable photodetectors with a responsivity of 42.1 A W⁻¹, a detectivity of 1.3 × 10¹⁴ Jones, high-fidelity image, photoplethysmography sensor functions, and high mechanical stability.