ИСТИНА

We report the realization of a new principle of gas detection using the resistive type sensor operating at RT under a low power visible light source. Bulk MOS are transparent in this spectral range. The solution of this problem becomes possible when sensitive materials are nanocomposites based on nanocrystalline MOS and photosensitizers. The role of photosensitizers consists in shifting the optical sensitivity range of semiconductor oxides towards larger wavelengths. The relative position of the energy bands of MOS and sensitizer must ensure the transfer of photoexcited carriers from the sensitizer to the semiconductor matrix. Selected photosensitizers: CdSe quantum dots (QDS) and organic dyes – Ru(II) complexes with organic ligands, are characterized by absorption in the visible range of the spectrum and have high extinction coefficients. The role of illumination consists in generation of electrons, which can be transferred into MOx conduction band, and holes that can recombine with the electrons previously trapped by the chemisorbed acceptor species and thus activate desorption of analyte molecules. Sensor measurements demonstrated that sensitized nanocrystalline MOS can be used for oxidizing gas detection under visible light illumination at RT without any thermal heating.