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In order to acquire a reasonable description of the structural, electronic and optical properties of the perovskite compound CsPbI 3 , first principle calculations have been computed by density functional theory implemented in the WIEN2k code. The calculations are presented within PBE-sol for exchange correlation functions coupled with modified-Becke-Johnson (mBJ) exchange potential. The (001) surfaces of CsPbI 3 for varying thicknesses have been constructed using the Structeditor program implemented in the WIEN2k code. The lattice constant, band gap and DOS have been computed. The CsPbI 3 bulk and surface exhibit a direct band gap located at the R symmetry point of the Brillouin zone. The band gap approaches experimental values when the exchange correlation function is coupled with mBJ. The optical properties of CsPbI 3 were computed in terms of dielectric properties, refractive index, extinction coefficient, absorption coefficient, conductivity, reflectivity and energy loss. The direct band gap nature and high-absorption power of the surfaces of CsPbI 3 in the (001) direction in the infrared, visible and ultraviolet energy range make it suitable for use in optical and optoelectronic devices.

This study compares photovoltaic and electrochemical properties of nano sized ZnO–SnO2 composite as photoanode material made by a simple but effective mechanical mixing method with Ru N719 dye for energy harvesting applications in DSSCs.

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C, N, S co-doped TiO2 (TU-TiO2) synthesized through solid state method using high energy ball milling was applied onto fluorine doped tin oxide (FTO) glass substrate and sintered at 450° C for half hour for use as a photoanode of dye-sensitized solar cells (DSSCs). Natural Betalain containing dye extracted from beetroot was used as sensitizer, Iodide triodide was used as electrolyte and graphite as counter electrode to obtain FTO/C, N, S-TiO2/Dye/Electrolyte/Graphite/FTO DSSC. X-ray Diffraction analysis established the formation of single phased materials retaining the basic TiO2 structure. Optical properties were enhanced with increase in molar concentration of thiourea in TiO2. Fourier Transform Infrared spectroscopy confirmed the incorporation of sulphur into TiO2. The highest of 94% relative increase is observed in solar to electric conversion efficiency for C, N, S co-doped TiO2 compared to un-doped TiO2. Along with decrease in the band gap making the cell more sensitive to visible light, the improved performance is also due to the rise in charge injection from betalain dye to the C, N, S co-doped TiO2.