High-Performance Optoelectronic Gas Sensing Based on All-Inorganic Mixed-Halide Perovskite Nanocrystals with Halide Engineering

Gas sensors are of great interest to portable and miniaturized sensing technologies with applications ranging from air quality monitoring to explosive detection and medical diagnostics, but the existing chemiresistive NO₂ sensors still suffer from issues such as poor sensitivity, high operating temperature, and slow recovery. Herein, a high-performance NO₂ sensors based on all-inorganic perovskite nanocrystals (PNCs) is reported, achieving room temperature operation with ultra-fast response and recovery time. After tailoring the halide composition, superior sensitivity of ≈67 at 8 ppm NO₂ is obtained in CsPbI₂Br PNC sensors with a detection level down to 2 ppb, which outperforms other nanomaterial-based NO₂ sensors. Furthermore, the remarkable optoelectronic properties of such PNCs enable dual-mode operation, i.e., chemiresistive and chemioptical sensing, presenting a new and versatile platform for advancing high-performance, point-of-care NO₂ detection technologies.