Perovskite Photodetectors on Skin: Current Advances and Commercialization Challenges
Flexible perovskite photodetectors (FPDs) are critically evaluated as alternatives to rigid silicon-based photodetectors for wearable health monitoring, environmental sensing, and human-machine interfaces. Metal halide perovskites offer high absorption coefficients enabling sub-500 nm active layers, tunable band gaps spanning UV to NIR, and low-temperature solution processability (<150°C) compatible with PET and PI substrates. FPD architectures—photodiodes, photoconductors, and phototransistors—are compared, with self-powered heterojunction devices achieving dark currents of ~10^-12 A and detection of 3 nW cm^-2 at 0 V bias. Despite these metrics, commercialization is impeded by crystallization control during roll-to-roll (R2R) manufacturing, lead waste management, and long-term operational stability under coupled light-thermal-humidity stress. Lead-free alternatives based on Sn2+, Bi3+, and metal-free compositions, along with aqueous 'one-click restart' recycling achieving near-complete material recovery, are assessed. The analysis concludes that standardized accelerated aging tests, robust encapsulation, and closed-loop material circularity are prerequisites for scalable deployment.