Аннотация:Organic–inorganic hybrid halide perovskites exhibit a wide range of unique optoelectronic propertiesthat can be applied to a variety of semiconducting photoelectronic devices. There is also a growinginterest in using perovskites as sensor materials for detecting various gas-phase analytes. In the presentwork, we report the design and investigation of a gas sensor based on formamidinium lead chloride(FAPbCl3), which demonstrated a strong and highly selective response towards ammonia. Theseobservations were confirmed by our calculations to be due to a ‘‘lock-and-key’’ mechanism of theammonia molecule filling the chlorine-vacancy defect, which effectively healed the carrier trap createdby such a defect. A good reversibility and operational stability of the devices at room temperature wasalso observed, suggesting that complex lead halides are highly promising families of materials for gassensor and electronic nose applications.