Hybrid lead halide spin coated perovskite films have been successfully tested as portable, flexible, operated at room temperature, self-powered, and ultrasensitive ozone sensing elements. The electrical resistance of the hybrid lead mixed halide perovskite (CHNHPbICl) sensing element, was immediately decreased when exposed to an ozone (O) environment and manage to recover its pristine electrical conductivity values within few seconds after the complete removal of ozone gas. The sensing measurements showed different response times at different gas concentrations, good repeatability, ultrahigh sensitivity and fast recovery time. To the best of our knowledge, this is the first time that a lead halide perovskite semiconductor material is demonstrating its sensing properties in an ozone environment. This work shows the potential of hybrid lead halide based perovskites as reliable sensing elements, serving the objectives of environmental control, with important socioeconomic impact.

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Indium oxide (InOx) films with a thickness of 10–1100 nm were deposited onto Corning 7059 glass and silica substrates at various substrate temperatures. An unusual decrease of the lateral grain size with increasing substrate temperature during deposition was found. The changes in the conductivity of the films after exposure to ultraviolet light in vacuum and subsequent oxidation in ozone atmosphere were analyzed and related to their structural and morphological properties. It is suggested that the photoreduction and oxidation treatments affect only a thin layer less than 10 nm at the surface of the film, while the minimum bulk conductivity is mainly determined by the structural and morphological properties.

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