The present research work reports on the fabrication of ultraviolet (UV) photodetectors using bismuth ferrite (BiFeO3, BFO) thin films with varying thickness. Using the spray pyrolysis technique, BFO thin films were deposited on the glass substrate at 673 K. The deposited BFO thin films were characterized by Raman and FTIR spectroscopic analysis. The morphological analysis reveals uniform grain distribution for the prepared BFO samples. The optical analysis reveals that transmittance value decreases upon an increase in the thickness of BFO thin films and the calculated optical band gap value lies between 2.0 to 2.3 eV. The varying thickness of the BFO active layer was stacked between ITO and Al electrodes and the current–voltage (I–V) characteristics of the fabricated ITO/BFO/Al devices were studied under dark and UV illumination (λ = 365 nm). It was observed that BFO with an optimum thickness (365 nm) exhibits higher photoresponsivity of 110 mA/W with an external quantum efficiency (EQE) of 37.30%. The impact of different thickness of the BFO active layer, the role of adsorption and desorption of oxygen (O2) molecules upon the surface of BFO layers towards UV photoresponse characteristics were investigated.

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The present research reports on a hybrid multifunctional device for UV light detection and non-volatile resistive switching memory based on n-In:ZnO/poly 3,4-ethylene dioxythiophene:polystyrene sulfonate (PEDOT:PSS) junctions. Using a spray pyrolysis method, indium (1–5 at. %) doped ZnO thin films (IZO) were deposited on the pre-heated glass substrate. The structural analysis of IZO thin films shows that all the prepared samples exhibit a hexagonal wurtzite structure with preferential orientation along the (101) plane. The morphological analysis shows a uniform distribution of grains without any voids. The optical transmission spectra reveal that IZO thin films show higher transparency (>90%) in the visible region. With an optimum doping concentration of In (4 at. %), the deposited IZO thin films exhibit high carrier concentration and low electrical resistivity value of 4.58 × 1020 cm−3 and 4.01 × 10−2 Ω cm, respectively. The current–voltage (I–V), photoresponse, and resistive switching behavior of the fabricated n-IZO/PEDOT:PSS-based hybrid device was studied. Under an external reverse bias, the device exhibits a high photoresponsivity (R) value of 0.31 A/W and fast photoresponse switching speed with the measured rise and fall time of 0.08 and 1 s, respectively. It was proposed that the formation/rupture of both anionic and cationic conductive filaments plays a crucial role in the obtained resistive characteristics of the fabricated hybrid device.

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