Ambient Stable CsCuI Flexible Gas Sensors for Reliable NO Detection at Room Temperature.

The advancement of the Internet of Things and artificial intelligence has increased the demand for air quality monitoring to protect human health. Nitrogen dioxide (NO), a hazardous pollutant, causes inflammatory responses, even at low concentrations, necessitating sensitive gas sensors. Although metal oxide semiconductor sensors are commonly used, their high-operating temperature and reliance on additional heaters limit miniaturization and increase power consumption. Here, a lead-free, transparent, and flexible CsCuI halide perovskite gas sensor was developed, demonstrating high sensitivity (1509% to 5 ppm) and selectivity for NO detection at room temperature with full recovery. The sensor exhibited high stability in ambient air and high-humidity environments, which is not achievable with traditional halide perovskite sensors. First-principles density functional theory calculations revealed the mechanisms underlying its stability and sensitivity. This study highlights the potential of halide perovskites for low-power gas sensing at room temperature, addressing critical challenges for commercially viable wearable applications.