All-inorganic lead-free Cs2XCl6 (X = Hf, Zr, Te) perovskites for humidity detection

Lead halide perovskites are recently regarded as promising sensing materials owing to their sensitive surface characteristics and solution processability. However, the toxicity issue and intrinsic instability restrict their applications. Herein, lead-free Cs2XCl6 (X = Hf, Zr, Te) perovskites are employed to manufacture an environmentally friendly humidity sensor. With the assistance of quartz crystal microbalance (QCM), real-time and low-cost humidity sensors are performed. The as-prepared Cs2XCl6 (X = Hf, Zr, Te) humidity sensors exhibit ultrafast response/recovery behaviors (2.8 s/2.2 s, 3.8 s/2 s and 3.7 s/2.1 s) and considerable long-term stability (over 30 days). Furthermore, the bimodal exponential model is adopted to reveal the kinetics reactions of water molecules on the Cs2XCl6 (X = Hf, Zr, Te) coated QCM humidity sensors. All results suggest that the Cs2XCl6 (X = Hf, Zr, Te) coated QCM humidity sensors could be promising real-time humidity detection techniques.