Detecting ultra-low ozone and hydrogen concentrations with CsPbBr$_3$ microcrystals direct grown on electrodes.

Highly stable ozone and hydrogen sensing elements were fabricated based on well-crystalline rounded cube-shaped CsPbBr$_3$ submicron crystals, synthesized by a facile solution process performed under ambient conditions. It is shown that such elements demonstrate enhanced room temperature gas sensing ability compared to the previously reported metal halide and oxide-based ones. Electrical measurements performed on these sensing components revealed high response to ultra-low ozone and hydrogen concentrations, namely 4 ppb and 5 ppm respectively, as well as an impressive repeatability of the sensing behavior even after a few months of storage in ambient conditions. Both ozone and hydrogen detecting sensors were self-powered, i.e. they do not require the use of UV or heating external stimuli, and exhibited fast detection and short restoration times. These attractive properties along with the simple synthesis conditions could provide an easy, efficient and low-cost potential technology for the realization of future gas sensing devices.