Real-time and ultrasensitive humidity sensor based on lead-free Cs2SnCl6 perovskites

Benefiting from the environmental sensitivity, perovskite materials show great potentials in sensor devices. Especially, humidity sensors are regarded as reversing disadvantage to advantage of the metal halide perovskites. However, the low stability and the toxicity of lead are the major impediment to practical applications for humidity sensors. Herein, in this work, we prepared Cs2SnCl6 perovskites by a solution-phase synthesis method and demonstrated the excellent humidity sensing property of lead-free perovskite Cs2SnCl6-based sensors. The fabricated humidity sensors exhibit an ultrahigh impedance change of 2.2E6 from relative humidity (RH) of 11–95% and a short response time (0.8 s) and recovery time (5.4 s), which possesses great potentials in real-time moisture detection. Furthermore, it also presents a good capability of reversibility and an impressive stability. The underlying humidity sensing mechanism under different humidity conditions is also discussed in detail. Our results provide a simple, economic and environmental-friendly method for preparing superior-performance and real time humidity sensor.