Ambient Stable CsCu<sub>2</sub>I<sub>3</sub> Flexible Gas Sensors for Reliable NO<sub>2</sub> Detection at Room Temperature
Seung Ju Kim, Gi Baek Nam, Yeong Jae Kim, Tae Hoon Eom, Jung‐El Ryu, Hyuk Jin Kim, Hyeon-Ji Lee, Ho Won Jang
Abstract
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 2 ), 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 CsCu 2 I 3 halide perovskite gas sensor was developed, demonstrating high sensitivity (1509% to 5 ppm) and selectivity for NO 2 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.