Effect of copper doping on plasmonic nanofilms for high performance photovoltaic energy applications.

In the current era, alternative but environment-friendly sources of energy have gained attention to meet the growing energy demands. In particular, the focus of research has been solar energy and using it to fulfill energy demands. Solar energy is either directly converted into electrical energy or stored for later use. Solar cells are a practical way to turn solar energy into electrical energy. Various materials are being investigated to manufacture solar cell devices that can absorb a maximum number of photons present in sunlight. The present study reports thermally evaporated in situ Cu-doped SnS photon absorber thin films with tunable physical properties. This study mainly explored the effects of changing Cu concentrations on the physical features of light absorption of SnS thin films. The thin films were formed by simultaneous resistive heating of Cu and SnS powders on glass substrates at 150 °C. The X-ray diffraction patterns revealed pure SnS thin films having orthorhombic polycrystalline crystal structures oriented preferentially along the (111) plane. Raman spectroscopy confirmed this phase purity. Photoconductivity studies showed phase dependence on Cu content that improved with increasing concentrations of Cu. The optical bandgap energy was also found to be dependent on Cu content and was observed at 1.10-1.47 eV for SnS thin films with variation in the Cu content, i.e., 0-18%. According to the hot probe method, all films displayed p-type conductivity for the substitution of Cu metal atoms. These findings demonstrated that the prepared thin films are substantial candidates as low-cost, suitably efficient, thin-film solar cells featuring environmentally-friendly active layers that absorb sunlight.

Structural, dielectric and electrical properties of Gd-substituted lithium nano-ferrites prepared by the WOWS sol-gel method.

To synthesize lithium ferrite with various Gd concentrations (Li0.5Fe2.5-xGdxO4), x = 0.00, 0.025, 0.05, 0.075, 0.1, solutes were dissolved in glycol, i.e. by using the without water and surfactant (WOWS) sol-gel method. X-ray diffraction (XRD) analysis confirmed that the material possessed an inverse spinel cubic structure and is single phase. Pellets of all samples were sintered at 700 °C and XRD confirmed that samples were crystalline, phase pure and had an inverse spinel cubic lattice. Scanning electron microscopy indicated that the grains were agglomerated and had a predominantly spherical shape. It is concluded that Gd acts as a grain refiner in lithium ferrite up to a Gd concentration of 0.05. AC conductivity and dielectric constant increased by increasing Gd concentration. The Maxwell-Wagner model and Johnsher's power law were used to explain the dielectric properties. DC conductivity was measured from 100 to 600 °C. DC conductivity was explained by the hopping mechanism. It is concluded that DC resistivity and dielectric constant values are related reciprocally in the prepared sample. AC electrical properties were also measured at a constant frequency of 1 MHz in the temperature range from 400 to 600 °C. Gd-substituted lithium ferrite showed high AC conductivity, high DC resistivity and constant dielectric values, but low dielectric loss values as compared to pure lithium ferrite.