Cs₂AgBiBr₆ Perovskites: Designing Stable, Sensitive and Selective Eco‐friendly Ozone Sensors

Lead halide perovskites have shown great promise for gas sensing applications due to their ability to detect and respond to gas exposures at room temperature. However, the toxicity of lead raises concerns, hindering their widespread use. To address this limitation, this study explores the potential of the lead (Pb)‐free Cs 2 AgBiBr 6 perovskite as a sensing element for room‐temperature gas detection. This eco‐friendly sensor, synthesized at room temperature without the use of harmful organic solvents, operates at low voltage (0.1 V) minimizing energy consumption. The perovskite material is synthesized using a precipitation method under ambient conditions, ensuring a cost‐effective and environmentally friendly fabrication process. The influence of morphology on ozone (O 3 ) sensing performance is investigated, revealing that the microsheets exhibit the highest sensitivity. The sensor also demonstrates remarkable stability over time and under various humidity and temperature conditions, ensuring its reliable and robust performance in diverse environments. Notably, the sensor exhibits exceptional selectivity to O 3 over other gases, including nitric oxide (NO), hydrogen (H 2 ), methane (CH 4 ), and carbon dioxide (CO 2 ). This selectivity, along with the interaction between the gases and the perovskite surface, is confirmed through both experimental measurements and first‐principles calculations. This technology holds immense potential for applications in air quality monitoring and industrial safety.