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Cadmium sulfide nanoparticles were prepared by chemical coprecipitation method using cadmium ace... more Cadmium sulfide nanoparticles were prepared by chemical coprecipitation method using cadmium acetate
and, sodium sulfide usingand tetrabutylammonium bromide (TBAB) as a capping agent. The synthesized
nanoparticles were characterized by using UVVis spectroscopic analysis, Xray diffraction analysis (XRD),
Field emission scanning electron microscopic analysis (FESEM), Energy dispersive Xray analysis (EDAX)
and BET surface area nitrogen adsorptiondesorption analysis. The band gap of capped CdS was calculated by
using UVVis absorption spectrum as 3.23 eV. The Xray diffraction pattern revealed that the synthesized
cadmium sulfide nanoparticles were polycrystalline nature with wurtzite hexagonal structure and crystallite
size was calculated as 7.2 nm by using Debye Scherer method. The surface area, pore volume and pore size
were found to be 93.15 m /g, 1.64 × 10 cm /g and 6.2 Å by BET nitrogen adsorptiondesorption analysis.
The dielectric constant, dielectric loss and AC conductivities were studied over a range of frequency (50 Hz–
5 MHz) and temperature (40–200 °C). Solar cell was fabricated using cadmium sulfide as photocathode
material, titanium dioxide as photoanode material, potassium iodide/iodine as an electrolyte solution,
ruthenium dye as a sensitizer and power conversion efficiency was found to be 2.7 %.

Zinc selenide and Mn doped ZnSe nanoparticles were synthesized by solvothermal method. The synthe... more Zinc selenide and Mn doped ZnSe nanoparticles were synthesized by solvothermal method. The synthesized nanoparticles were characterized by XRD, UV, PL, SEM and EDX spectral analysis. X-ray diffraction analysis confirmed a hexagonal wurtzite structure and the grain size were found to be 19.32 nm and 7.95 nm for pure and Mn doped ZnSe nanoparticles. The band gap energy was computed from the absorption data as 2.3 eV for ZnSe nanoparticles and 3.4 eV for Mn doped ZnSe nanoparticles. The EDX spectral analysis confirmed the purity of the samples. The solar cell was fabricated using TiO2 as a photoanode, pure and doped ZnSe as a counter electrode, ruthenium dye as sensitizer and I-/I 3-as electrolye and the maximum conversion efficiency of solar cell were found to be 3.21%. KEY WORDS: Solvothermal, Mn doped ZnSe nanoparticles, Dye sensitized solar cell. 1. INTRODUCTION Nanostructured materials are of significant interest, owing to their unique dimension dependent properties and useful applications as building blocks in electronics, optoelectronics, sensors and bio imaging. Among several nanostructures, II-VI band gap semiconductors have gained substantial consideration due to their wide applications in light –emitting diodes, photodetectors and colour displays. In particular, the wide band gap (2.8 eV) and considerably large binding energy (21 meV) of ZnSe, makes it an inorganic semiconductor for doped nanocrystals. The extended life time of charge carriers as observed in Mn doped ZnSe could be advantageous to improve the performance of solar energy conversion systems. DSSC Using ruthenium complex as photo sensitizers such as N3, N719 and black dyes has shown high photo conversion efficiency (PCE). The extent of diffusion of dye nanocrystalline TiO2 matrix significantly affects the efficiency and photocurrent in DSSCS. The electron transport at the dye and nanocrystalline semiconductor interface is a key step in the energy conversion process in which a photoexcited electron in dye molecules are transferred to external circuit through these semiconductor films. In this paper, ZnSe and Mn doped ZnSe nanoparticles were prepared via cost effective solvothermal method at 60 o C. The synthesized ZnSe nanoparticles characterized and the quantum conversion efficiency was measured by fabricating solar cell using the pure and Mn doped ZnSe as photo cathode which would act as cosenstizer, nanoporous TiO2 as a photo anode, ruthenium dye as sensitizers and I-/I 3-as electrolyte. 2. MATERIALS AND METHODS 2.1. Synthesis of ZnSe and Mn doped ZnSe nanoparticles: Zinc acetate and selenous acid were taken as 1: 1 ratio and dissolved in water by continuous stirring and capping agent poly ethylene glycol was added and stirring was continued for an hour. The reducing agent hydrazine hydrate was added with stirring and refluxed at 60 o C for 8 hours. The precipitate was centrifuged at 3000 rpm for complete separation of solid. The same procedure was adopted for the synthesis of Mn doped ZnSe nanoparticles. A 3% solution of manganese chloride was used in the synthesis of the doped nanoparticles. 2.2. Instrumentation: The synthesized ZnSe, Mn doped ZnSe sample were characterized by using X-ray diffractometer (MAC Science MO3XHF22) with Cu(Kα) radiation(λ = 1.5405Å) in the 2θ range of 10-80 o. Optical UV-vis absorption spectra of ZnSe were recorded using (schimadzu Uv-Vis 2700 spectrometer). Photoluminescence (PL) spectrum was recorded at room temperature using a Cary-Eclipse (ELO8O83851) spectrometer. Morphology was characterized by a scanning electron microscope SEM.JSM-7000. The current-voltage measurement of solar cell was characterized by GS610 YOGOKAWA source measure unit. 3. RESULTS AND DISCUSSION 3.1. Powder X-ray diffraction analysis: X-ray diffraction (XRD) patterns of ZnSe nanoparticles and the Mn doped ZnSe nanoparticles (fig.1) show intense diffraction peak indexed to (221), (311), (400), (304), (410) and (331) planes confirming wurtzite hexagonal structure (JCPDS file-046-1045). The increased intensity of the plane (311) in doped ZnSe may be due to high crystallinity in this plane of doping. The low intensity in undoped system may be due to imperfection or due to the strain or low crystallinity in the crystal. The average crystallite size of the particles has been estimated using the Debye-scherer formula. The average crystallite size of synthesized ZnSe

Graphene oxide was prepared from graphite powder using modified Hummer's method. Graphite and gra... more Graphene oxide was prepared from graphite powder using modified Hummer's method. Graphite and graphene oxide were characterised by X-ray diffraction studies, FTIR and UV spectral analysis. When graphite is oxidised to graphene oxide, peak at 2θ = 25-30 o disappear and a new peak at 10.78 o appears. The interlayer spacing, d of graphite and graphene oxide were calculated using Bragg's law as as 8.29Å. FTIR spectra confirmed the presence of oxygen containing functional groups on graphene oxide. The UV spectra reveal that graphene oxide has a good absorption in the visible region at 350-600 nm. Solar cells were fabricated using CdS nanoparticles as counter electrode, KI/I3-as electrolyte solution, Ruthenium complex as sensitizer and the active electrode was varied as TiO2-graphene oxide, graphene oxide and TiO2. The DSSC was fabricated to measure the photovoltaic performance.

Zinc sulfide nanoparticles were synthesized by chemical co-precipitation method from homogenous s... more Zinc sulfide nanoparticles were synthesized by chemical co-precipitation method from homogenous solutions of zinc nitrate and sodium sulfide in the presence of surfactant, tetrabutylammomium bromide (TBAB). The optical properties of surfactant-capped zinc sulfide nanoparticles were investigated using UV–visible absorption and photoluminescence spectral analysis. X-ray diffraction pattern of ZnS revealed the polycrystalline nature with cubic zinc blende structure and the grain size was calculated as 1.7 nm using Debye-Scherer method. The bandgap and optical size were calculated from the UV spectral data as 4.25 eV and 3.2 nm respectively. The morphology of ZnS nanoparticles were studied by Field emission scanning electron microscopic technique and their elements composition was confirmed by energy dispersive x-ray analysis (EDAX). Electrical properties of the as-synthesized ZnS nanoparticles were investigated by dielectric studies. The variation of dielectric constant, dielectric loss and AC conductivity studies were studied over a range of frequency (50 Hz to 5 MHz) and temperature (40 °C to 140 °C). Solar cell was fabricated using cadmium sulfide as photocathode material, TiO2-ZnS as photoanode material, potassium iodide / triiodide (KI/I3-) as an electrolyte solution, ruthenium red dye as a sensitizer and solar conversion efficiency was found to be 3.84%.

Cadmium oxide nanoparticles were prepared by precipitation method using cadmium acetate and ammon... more Cadmium oxide nanoparticles were prepared by precipitation method using cadmium acetate and ammonia solution. The synthesized CdO nanoparticles were characterized by using FTIR, X-ray diffraction studies (XRD), Field emission scanning electron microscopy (FE-SEM), Energy dispersive spectrometry (EDS), BET analysis, I-V characterisitics and dielectric studies. FTIR analysis confirmed the Cd-O bond formation in synthesized nanomaterial. The X-ray diffraction pattern revealed that synthesized cadmium oxide nanoparticles are face centered cubic with average crystallite size of 25 nm. The morphology and elemental composition were confirmed by FE-SEM and EDAX.The synthesized CdO nanoparticles showed high surface area of 31.5 m 2 /g, which enables high absorption of dye molecule in DSSC fabrication for increasing the efficiency of solarcell. The temperature and frequency dependence of dielectric constant, dielectric loss and AC conductivities were studied over a range of (50 Hz to 5 MHz) and temperature (40-200°C). Solar cell was fabricated using CdS as photo cathode material, TiO2/CdO as photo anode material, potassium iodide/iodine as electrolyte solution, ruthenium red dye as sensitizer and solar conversion efficiency was found to be 1.62%.

Cadmium sulfide nanoparticles were prepared by chemical precipitation method in aqueous medium us... more Cadmium sulfide nanoparticles were prepared by chemical precipitation method in aqueous medium using cadmium acetate and sodium sulfide. The synthesized nanoparticles were characterized by using UV-Vis studies, X-ray diffraction studies (XRD), field emission scanning electron microscopy (FESEM), energy dispersive x-ray analysis (EDAX) and BET analysis. The X-ray diffraction pattern revealed that the synthesized cadmium sulfide nanoparticles were polycrystalline nature and grain size 7 nm was calculated by using Scherer method. Specific surface area, pore volume and pore size were estimated by nitrogen adsorption-desorption analysis. The specific surface area of the synthesized material is 74.26 m 2 /g. The temperature and frequency dependence of dielectric constant, dielectric loss and AC conductivities were studied over a range of frequency (50 Hz to 5 MHz) and temperature (40-200°C). These results demonstrate that the CdS nanoparticles has a potential applications in DSSC's.