Photoresistive gas sensor based on nanocrystalline ZnO sensitized with colloidal perovskite CsPbBr3 nanocrystals

•Nanocomposite based on ZnO and colloidal CsPbBr3 nanocrystals was synthesized.•CsPbBr3 nanocrystalls sensitize photoconductivity ZnO in the visible range.•Periodic illumination was used for light-activated NO2 detection.•Tuning metal-oxide sensors performance by slight heating and light illumination.•Lead halide perovskite nanocrystals for gas sensing application were used. The development of sensor materials of which gas sensitivity activates under light illumination is of great importance for the design of portable gas analyzers with low power consumption. In the present work a ZnO/CsPbBr3 nanocomposite based on nanocrystalline ZnO and colloidal cubic-shaped perovskite CsPbBr3 nanocrystals (NCs) capped by oleic acide and oleylamine was synthesized. The individual materials and obtained nanocomposite are characterized by x-ray diffraction, low-temperature nitrogen adsorption, x-ray photoelectron spectroscopy, high angle annular dark field scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy mapping and UV–vis absorption spectroscopy. The spectral dependence of the photoconductivity of the ZnO/CsPbBr3 nanocomposite reveals a well-defined peak that strongly correlates with the its optical absorption spectrum. The nanocomposite ZnO/CsPbBr3 shows enhanced photoresponse under visible light illumination (λmax = 470 nm, 8 mW/cm2) in air, oxygen and argone, compared with pure nanocrystalline ZnO. Under periodic illumination in the temperature range of 25−100 °C, the ZnO/CsPbBr3 nanocomposite shows a sensor response to 0.5–3.0 ppm NO2, unlike pure nanocrystalline ZnO matrix, which demonstrates sensor sensitivity to NO2 under the same conditions above 100 °C. The effects of humidity on the sensor signal and photoresponse are also discussed.