Ambient Stable CsCu<sub>2</sub>I<sub>3</sub> Flexible Gas Sensors for Reliable NO<sub>2</sub> Detection at Room Temperature.

Kim, Seung Ju; Nam, Gi Baek; Kim, Yeong Jae; Eom, Tae Hoon; Ryu, Jung-El; Kim, Hyuk Jin; Lee, Hyeon-Ji; Jang, Ho Won · Nano Lett · 2025

basic_science · Level V

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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<sub>2</sub>), 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<sub>2</sub>I<sub>3</sub> halide perovskite gas sensor was developed, demonstrating high sensitivity (1509% to 5 ppm) and selectivity for NO<sub>2</sub> 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.