Effect of oxygen vacancy concentration on indium tungsten oxide UV-A photodetector

Annealing effect on the physical properties of TiO2 thin films deposited by spray pyrolysis

Titanium dioxide (TiO2) thin films were deposited on glass substrates at 350 °C using the spray pyrolysis technique. As deposited and annealed thin films were characterized by X-ray diffraction, scanning electron microscopy, UV-VIS spectroscopy, and photodetection. Unlike the as deposited samples which were amorphous, annealed samples show an anatase phase. Films were absorbent in the UV region and the band gap energy decreases from 3.78 eV to 3.4 eV with annealing. The photoresponse of TiO2 photodetectors was recorded under UV (λ1 = 365 nm, λ2 = 254 nm) and visible light illumination by reversible switching (ON/OFF) cycles using DC electrical characterization. Photosensitive properties such as reproducible photosensitivity, responsivity, and detectivity were also studied.

Solution processed transparent anatase TiO2 nanoparticles/MoO3 nanostructures heterojunction: high performance self-powered UV detector for low-power and low-light applications

Ultraviolet (UV) photodetectors are considered as the major players in energy saving technology of the future. Efforts are needed to further develop such devices, which are capable of operating efficiently at low driving potential as well as with weak illumination. Herein, we report an all-oxide, highly transparent TiO2/MoO3 bilayer film, with nanoparticulate anatase TiO2 as the platform, fabricated by a simple solution based method and demonstrate its use in UV photodetection. Photoconductivity measurement with 352 nm light reveals the self-powered UV detection capability of the device due to the built-in potential at the bilayer interface. The device exhibits a high photoresponsivity (46.05 A W-1), detectivity (2.84 × 1012 Jones) and EQE (16 223%) even with a weak illumination of 76 μW cm-2, at a low bias of only -1 V. The self-powered performance of the bilayer device is comparable to that of commercial Si photodetectors as well as other such UV detectors reported based on metal oxide heterojunctions. The improved and faster photoresponse shown by the device is due to the formation of an effective heterojunction, as evidenced by XPS, electrochemical and I-V studies. It can be further attributed to the better charge transport through the densely aligned nanostructures, reduced recombination and the better mobility of anatase TiO2 nanoparticles. The performance is best-in-class and proves the potential of the transparent heterojunction to be used in highly responsive, self-powered UV detectors for low bias, low light applications.