Ultrahigh Response Humidity Sensor Based on Lead-Free Cs2SnCl6 Perovskite Films

The humidity sensor based on quartz crystal microbalance (QCM) has a remarkable advantage for Internet of Things (IoT) applications owing to its digital output. Herein, one lead-free perovskite Cs ₂ SnCl ₆ film is employed to manufacture a QCM-based humidity sensor, and the practical application on IoT is successfully performed. The fabricated humidity sensor exhibits a logarithmic linearity response and an ultra-high response of 7289 Hz for the relative humidity ranging from 11% to 85%. Furthermore, the Langmuir adsorption model is adopted to reveal the adsorption kinetics of the water molecules on the Cs ₂ SnCl ₆ film. These results suggest that the proposed humidity sensor could be a promising candidate for remote and smart humidity sensors.