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The sensitivity reduction mechanisms in organic perovskite X-ray detectors are investigated in this paper by considering the dynamics of charge carrier transport across the perovskite photoconductor. A numerical model is proposed by considering bimolecular recombination, space charge effects, charge carrier trapping (monomolecular) and detrapping. The coupled continuity equations for both holes and electrons, trapping rate equations, and Poisson’s equation across the photoconductor are simultaneously solved by a finite difference method. The numerical results are compared with COMSOL simulation. The change of sensitivity is not significant for a usual single exposure in diagnostic medical X-ray imaging applications. However, the sensitivity starts decreasing rapidly for an order of magnitude higher dose rate or accumulated dose under repeated exposures. The rapid change of electric field distribution (i.e., non-uniform electric field) is mainly responsible for the reduction of X-ray sensitivity in perovskite X-ray detectors.

In the present investigation, compact TiO2 thin film was prepared by using an artist spray gun (ASG)-assisted pyrolysis method to use as an electron transport layer (ETL) for perovskite solar cell (PSC). The influence of the distance between the spray gun nozzle and the substrate was studied to get quality TiO2 thin film onto FTO substrate among three different distantly deposited TiO2 thin films. The formation of anatase TiO2 thin film was confirmed by XRD and Raman spectroscopy studies. The bandgap of this thin film was measured by UV–Vis analysis and it was found to be 3.19 eV. The emission spectrum and charge separation of TiO2 thin film were analysed by photoluminescence studies. The emission spectrum of TiO2 thin film exhibited at 380 nm confirmed the indirect transition from the conduction band to the valence band. The FE-SEM image confirmed that the prepared TiO2 thin film was uniformly deposited over the substrate without any pinhole, which shows a good agreement with the Raman mapping analysis. A power conversion efficiency (PCE) of 2.69% has been achieved with Pb-free PSC fabricated from uniformly deposited TiO2 ETL.

Pure and other concentrations of cobalt (Co2+) ions incorporated into cuprous oxide Cu2−xCoxO (x = 0–14 mM) thin films were successfully deposited in fluorine-doped tin oxide (FTO) glass substrate by employing electro deposition technique. The crystallite size of pure and Co-doped thin films was investigated from 29.03 to 43.38 nm using X-ray diffraction (XRD) patterns. Scanning electron microscope (SEM) images display three-sided pyramid shape morphology of pure Cu2O thin films that get significantly changed, as and when Co concentrations get increased. The optical bandgap value gets continuously increased from 2.128 to 2.297 eV for a 0–14 mM change in Co doping concentration. Vibrating sample magnetometer (VSM) pictures the film that exhibits a better ferromagnetic property with a saturation magnetism of 159.96 E−6 emu for 14 mM Co dopant. X-ray photoelectron spectroscopy (XPS) confirm the presence of cobalt (Co2+) as a dopant in the host Cu2O thin films. The Cu2−86Co14O (x = 14 mM) thin film has a higher specific capacitance of 164.90 F/g with 3.66 Wh/kg energy density at the current density of 2 A/g. It has a good energy and a power density in the higher concentration Co-doped Cu2O thin films applicable for energy storage devices.

In this study, we report the synthesis of manganese tungstate (MnWO4)/graphitic carbon nitrides (g-C3N4) hybrid photocatalysts by simple hydrothermal method. The prepared photocatalysts have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, photoluminescence spectroscopy (PL) and UV–visible spectroscopy. XRD and TEM results reveal that the both pure and composite samples have monoclinic wolframite structure with spherical nanoparticles, which is decorated on the surface of g-C3N4 sheets. A considerable red shift in the absorption and narrowing the band gap (3.02–2.55 eV) energy was observed in the MnWO4/g-C3N4 composite samples. The photocatalytic measurements exhibit that the optimized photocatalyst (15 wt%-MnWO4/g-C3N4) show high degradation efficiency (98%) and long-term stability towards rhodamine (RhB) dye under visible light irradiation. The J-V characteristics reveal that MnWO4/g-C3N4 photoanode show high photo-conversion efficiency (PCE%) of 7.15%, which is higher than that of pure MnWO4 (2.34%). The significant enhancement in the photocatalytic behavior is due to the coactions between the g-C3N4 nanosheets and MnWO4 nanoparticles.

Pristine and Fe incorporated cuprous oxide Cu2−xFexO (x = 0–3 mM) thin films were deposited on the Fluorine doped Tin Oxide (FTO) glass substrate by employing electrochemical deposition technique in an aqueous solution containing CuSO4 and FeSO4 sources. The deposited thin films were characterized with the help of X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Photoluminescence (PL), UV–Vis-NIR Spectroscopy, LCR Measurement and Vibrating Sample Magnetometer (VSM) to investigate the structural, morphological, optical, electrical and magnetic properties respectively. XRD patterns confirm about the presence of pristine and Fe incorporated Cu2O films which are in cubic structure and are grown along with their (111) preferential growth orientation. SEM images display that a three sided pyramid shaped morphology of the Cu2O thin films have significantly got changed with an increase in Fe concentrations. Photoluminescence (PL) spectra show a near band edge emission around 495 nm which are in good agreement with optical band gap of UV–Vis spectra. Temperature dependent LCR measurements illustrate that the conductivity of film decreases with an increase in the Fe dopant concentration. Vibrating Sample Magnetometer (VSM) measurement enables in understanding that the diamagnetic nature of pristine Cu2O thin film gets obviously transformed into ferromagnetic nature as the Fe concentration gets increased from 0 to 3 mM. XPS spectra enables in knowing that the 3 mM Fe doped Cu2O thin films exhibit Fe3+ ions which are substituted in Cu2O lattice.

A numerical model is developed to describe the electron–hole pair (EHP) creation energy in amorphous selenium (a-Se) for high energy photon excitation by solving the three dimensional coupled continuity equations of electrons and holes considering carrier drift, diffusion and bimolecular recombination between non-geminate electrons and holes. The numerical model is fitted with the published experimental results on widely varying X-ray energy, electric field and temperature. The model shows a good agreement. The results of this paper indicate that the columnar recombination model is capable of describing the electric field, temperature, and photon energy dependent EHP creation energy in a-Se for high energy photons.

Enhancing the sensitivity of a direct conversion flat panel X-ray imaging detector with minimum manufacturing cost has been a major dream for long decades. This criterion has been recently addressed by the usage of MAPbX3 (MA is CH3NH3 and X is a halogen atom such as Cl, I, or Br) perovskite in X-ray imaging detectors. Though MAPbI3 has shown large area deposition capability and good X-ray sensitivity, it has to fulfil other criteria such as low dark current, high spatial resolution and high signal to noise transfer capabilities. This paper evaluates the imaging performances such as X-ray sensitivity, detective quantum efficiency (DQE) and modulation transfer function (MTF) of organic perovskites (e.g., MAPbI3 and MAPbBr3) with comparison to amorphous selenium (a-Se). These perovskite materials have slightly higher linear attenuation coefficients than a-Se and the expected X-ray sensitivity of these two perovskite photoconductors are higher than a-Se. The mechanisms of the dark current and photocurrent gain in MAPbI3 detector are also investigated. The MAPbI3 detector shows some photocurrent gain, which is due to the enhanced electron injection under X-ray illumination. The expected theoretical zero spatial frequency DQE of the MAPbI3 detectors is similar to that of a-Se while the MAPbBr3 detector establishes a better DQE than a-Se. The expected MTF of the MAPbBr3 detectors is similar to that of a-Se while the MAPbI3 shows worse resolution than a-Se. Based upon our theoretical investigation, we believe that the organic perovskite can find its state of the art in near future if rigorous research for improving the charge carrier transport properties and optimizing its detector structure for low dark current were to be made.

The present study reports the antibacterial activities of undoped and Ag (2 at.%) + Co (5 at.%) doped ZnO nanopowders synthesized using combustion method. The synthesized particles have been tested to find the effect of doping on the antibacterial activities against two different pathogens namely Shigella flexneri and Bacillus Cereus. Further structural, morphological, chemical, compositional and optical properties were studied using X ray diffractometer (XRD), Field emission scanning electron microscope (FESEM), Transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy and Photoluminescence spectroscopy, respectively. The results reveal that Ag + Co doped ZnO shows better antibacterial activity against both the tested bacterial strains when compared with bare ZnO. The possible mechanism for the antibacterial activity of Ag + Co doped ZnO is reported

In this report, photocatalytic degradation of Acid Blue 113 (AB 113) has been investigated in aqueous heterogeneous media containing pure and Sm3+ doped ZnO nanostructures. A simple low frequency (42 kHz) ultrasound was employed to synthesize the nanostructures. X-ray diffraction, UV–Vis-NIR and Photoluminescence analyses revealed that Sm3+ ion was successfully doped into ZnO lattice. The organic solvents and dopant highly influenced the particle morphology which was identified through transmission electron microscopy. The photocatalytic efficiency was highly depended on the native defects and dopant. Sm3+ doped ZnO nanostructures demonstrated better photocatalytic degradation of the AB 113 due to the involvement of more oxygen vacancy defects, oxygen interstitials and Sm3+ ions in the charge recombination process and enhanced the better catalytic reaction under a UV-A lamp.

Copper indium sulphide films were deposited for the first time by the brush plating technique at different electrolyte temperatures in the range of 30–80 °C and at a constant deposition current density of 5.0 mA cm−2. The Films exhibited single phase copper indium sulphide. The grain size increased with increase of electrolyte temperature. Optical band gap of the films varied in the range of 1.30–1.42 eV. Atomic force microscopy studies indicated that the grain size vary from 600 to 1,000 nm, with increase of substrate temperature. Solar cells fabricated with the films exhibited Voc of 650 mV, Jsc of 19.5 mA cm−2, ff of 0.73 and efficiency of 9.50 %.

Copper indium telluride (CIT) films were deposited for the first time by the brush plating technique at different substrate temperatures in the range of 30–80 °C and at a constant deposition current density of 1 mA cm−2.The Films exhibited single phase CIT. The grain size increased with increase of substrate temperature. Optical band gap of the films varied in the range of 0.98–1.00 eV. Atomic force microscopy studies indicated that the grain size and surface roughness vary from 20 to 50 nm and 1.0 to 1.5 nm, respectively with increase of substrate temperature. The films exhibited photoconductivity.