An ultra-sensitive humidity sensor based on lead-free halide perovskite Cs2TeI6 for real-time human breath and finger monitoring

Abstract

Lead halide perovskites have been investigated for humidity sensors as they have shown outstanding success in optoelectronic applications but still suffer from some inherent instability and toxicity issues. In this work, we synthesized the all-inorganic, lead-free halide perovskite Cs2TeI6 by a hydrothermal method and demonstrated its impedimetric humidity-sensitive performance for the first time. The Cs2TeI6 sensor exhibits an ultra-high impedance variation of 4.25 × 103 with a response time of 3 s at a relative humidity (RH) of 11–97% and offers good reversibility and impressive stability. On this basis, a human respiration monitoring sensor and a relative humidity non-contact finger sensor were simulated to perform real-time humidity detection in relation to the human body. Our results provide a favorable candidate for humidity detection and further provide new insights into high-performance sensory devices using lead-free halide perovskites for real-time touchless physiological monitoring.