Perovskite‐Induced Ultrasensitive and Highly Stable Humidity Sensor Systems Prepared by Aerosol Deposition at Room Temperature

A new capacitive‐type humidity sensor is proposed using novel materials and fabrication process for practical applications in sensitive environments and cost‐effective functional devices that require ultrasensing performances. Metal halide perovskites (CsPbBr3 and CsPb2Br5) combined with diverse ceramics (Al2O3, TiO2, and BaTiO3) are selected as sensing materials for the first time, and nanocomposite powders are deposited by aerosol deposition (AD) process. A state‐of‐the‐art CsPb2Br5/BaTiO3 nanocomposite humidity sensor prepared by AD process exhibits a significant increase in humidity sensing compared with CsPbBr3/Al2O3 and CsPbBr3/TiO2 sensors. An outstanding humidity sensitivity (21426 pF RH%−1) with superior linearity (0.991), fast response/recovery time (5 s), low hysteresis of 1.7%, and excellent stability in a wide range of relative humidity is obtained owing to a highly porous structure, effective charge separation, and water‐resistant characteristics of CsPb2Br5. Notably, this unprecedented result is obtained via a simple one‐step AD process within a few minutes at room temperature without any auxiliary treatment. The synergetic combination of AD technique and perovskite‐based nanocomposite can be potentially applied toward the development of multifunctional sensing devices. An ultrasensitive and highly stable humidity sensor is fabricated through perovskite/ceramic nanocomposite layers using a simple and cost‐effective aerosol deposition process. The porous perovskite in the device plays an important role in the resultant massive polarization effect under low humidity, resulting in high sensitivity in the dynamic humidity range. This model can be widely implemented in various industrial fields.