Dimensional reduction in Cs2AgBiBr6 enables long-term stable Perovskite-based gas sensing

Halide perovskite gas sensors have a low gas detection limit at room temperature, surpassing the performance of traditional metal oxide chemiresistors. However, they are prone to structural decomposition and performance loss due to the lack of coordination unsaturated surface metal ions and sensitivity to environmental factors such as water, oxygen, heat, and light. To address this issue, we present a general strategy: replacing the cation Cs+ in inorganic perovskite Cs2AgBiBr6 with long-chain alkylamines. This modification synthesizes perovskite sensor materials that effectively block moisture and exhibit excellent stability under real-working conditions. The chemiresistors show high sensitivity and stability to CO gas, with (BA)4AgBiBr8 detecting CO at a limit of 20 ppb, maintaining performance after 270 days of continuous exposure to ambient air. The exceptional performance of (BA)4AgBiBr8 is elucidated through density functional theory calculations combined with sum frequency generation spectroscopy, marking a significant breakthrough in halide perovskite-based gas sensing by surpassing the stability and sensitivity of traditional sensors.