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In the present work, thin films of nickel cobalt oxide and polyvinyl alcohol nanocomposite (NCO-PVA) are prepared by chemical methods. The as-prepared NCO-PVA films have been structurally studied by X-ray diffraction and Fourier transform infrared spectroscopy. The morphology of the NCO-PVA films has been studied by Field emission scanning electron microscopy and High-resolution transmission electron microscopy. X-ray diffraction analysis has been used to study its crystallinity and phase. The optical properties of NCO-PVA nanocomposite films have also been studied. The surface area and pore size measurements have also been done. The UV-Vis spectrum analysis reveals that the films possess two direct band gaps (2.91 eV and 3.48 eV). The red shift of Photoluminescence emission has been observed for nanocomposite films with increasing excitation intensity. The AC electrical conductivity of NCO-PVA films has been studied as the high value of AC conductivity is essential for getting high power and high energy density in supercapacitors. Also, the high value of the dielectric constant of nanocomposite at small frequencies shows its supercapacitive nature. A short relaxation time (~6.37 ≤ 10−7 s) reveals a very small delay in molecular polarization along with changing the electric field, suggesting fewer energy losses. Electrochemical performance is checked by cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy measurements using 1 M Na2SO4neutral aqueous electrolytic solution. Also, the symmetric supercapacitor has been fabricated, using NCO-PVA films as the electrodes, which exhibits the specific capacitance value of50 F g−1and energy density of 18.9 W h kg−1. The results reveal that the prepared nanocomposite films have enough potential for supercapacitor device fabrication, especially the flexible supercapacitors.

Nanocrystalline Zn doped CdSe thin films with different Zn contents are prepared by thermal evaporation using the Inert Gas Condensation technique. The prepared samples are characterized by Energy dispersive X-ray spectroscopy (EDX), Scanning electron microscope (SEM), X-ray diffractometer (XRD), UV–Vis-IR spectrophotometer and Photoluminescence (PL) techniques, respectively. SEM investigation reveals uniform distribution of the films over the entire substrate surface. XRD results indicate that Zn doped CdSe thin films grew with the hexagonal phase. The variation of the optical band gap with change in Zn dopant concentration has been studied. PL intensity increases for Zn 5% doped nanocrystalline CdSe thin films as compared to doping with Zn 1%. Electrical investigations have also been made for nanocrystalline Zn 1% and Zn 5% doped CdSe thin films. Hall measurements indicate that Zn 1% and Zn 5% doped CdSe thin films are of n type.

Nanocrystalline thin films of CdSe:In 1% and CdSe:In 5% are prepared by thermal evaporation using the Inert Gas Condensation method. The effects of different doping concentrations of In have been investigated. X-ray diffraction, optical absorption, Photoluminescence (PL) and electrical techniques are used to characterize the films. X-ray diffraction measurements indicate that the nc-CdSe:In 1% and nc-CdSe:In 5% thin films possess hexagonal structure. The crystallinity of the films and the grain size decreases as the In doping concentration increases. The results of PL measurements indicate that the PL intensity decreases as the In doping concentration increases. The optical band gap values increase as the In doping concentration increases. The dc electrical conductivity increases from undoped nc-CdSe to nc-CdSe:In 1% and decreases for nc-CdSe:In 5%. The density of the states near Fermi level N ( E F ), degree of disorder ( T o ), hopping distance ( R ) and hopping energy ( W ) near the Fermi level are calculated using dc conductivity measurements at low temperatures. The effect of In doping concentration on these parameters is discussed. Hall measurements are performed on nc-CdSe, nc-CdSe:In 1% and nc-CdSe:In 5% to calculate the carrier concentration, carrier type and mobility of charge carriers.

Thin films of the undoped nanocrystalline CdSe (nc-CdSe) and doped (Zn and In) thin films have been prepared by physical vapor deposition in the presence of argon as inert gas at room temperature. The influence of the doping materials on the stoichiometry, grain size and trap parameters has been explored by means of Energy Dispersive X-ray Spectroscopy (EDX), Transmission Electron Microscopy (TEM) and thermally stimulated current (TSC) measurements. The TEM results show that small particles of nanometer range are formed in thin films and that size increases slightly with Zn doping and decreases when In is used as the doping material. TSC measurements in the temperature range from 225 to 350 K are performed at different heating rates. Well defined TSC peaks have been observed. The peaks shift to higher temperatures as heating rate is increased. Trap parameters, such as trap depth and density of traps have been determined. The trap parameters have been evaluated by using Gaussian fit and different heating rates methods. Good agreement has been obtained between trap parameters calculated from these two methods. It is observed that the trap depth decreases and trap density increases in doped samples compared to undoped ones.

nc-CdSe:Cu 1% and nc-CdSe:Cu 5% thin films have been deposited on glass substrates by thermal vacuum evaporation using the Inert Gas Condensation (IGC) method. Transmission Electron Microscopy (TEM) analysis reveals that the particles are spherical in shape and average particle size increases as the Cu concentration increases. The atomic weight percentage of Cu is determined by the Energy Dispersive X-ray analysis (EDX). X-ray Diffraction (XRD) measurements indicate that the films exhibit hexagonal structure. The grain size calculated from XRD increases as the Cu concentration is increased to 5%. The optical band gap E g opt has been determined from the absorption coefficient values using the Tauc’s procedure. A decrease in the band gap is observed with increase of the Cu concentration. The refractive index (n) is determined from transmittance using the Swanepoel’s method. The refractive index is found to depend on Cu concentration. The Photoluminescence (PL) spectral variation at different concentrations of Cu is studied.