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The present paper reports the synthesis, photoluminescence and thermoluminescence (TL) studies of Mn 2+ and Eu 2+ doped Zn2SiO4. The sample was prepared by the modified solid state reaction method, which is the most suitable for large-scale production. The prepared phosphor sample was characterized using Powder XRay Diffraction (PXRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), photoluminescence (PL) and Thermoluminescence (TL) techniques. The PL emission was observed in the range 400-650 nm ranges green regions for the Mn 2+ and Eu 2+ doped Zn2SiO4. Excitation spectrum found at 267, 278 and 314nm. Sharp intense peaks found around 490, 544 and 552nm with high intensity. From the XRD data, using the Scherer's formula, the calculated average crystallite size of phosphor is around few microns. Thermoluminescence study was carried out for the phosphor with UV irradiation with linear heating rate 6.7 0 C s -1 . The kinetic parameters are calculated by (Computerized glow curve convolution technique) CGCD technique.

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Phosphor doped with erbium ion with variable concentration (0.5-2 mol%) was synthesized by solid state reaction method. CaY 2 O 4 :Er 3+ phosphor is characterized by X-ray diffraction technique for structural analysis and crystallite size calculation. Average crystallite size was found to be nearly 58 nm. Two prominent TL glow peaks found at 163 ∘ C associated with higher temperature peak 340 ∘ C. The peak intensity of higher temperature (340 ∘ C) peak was less as compared to lower temperature peak (163 ∘ C) because the deep trapping formation is less in case of UV irradiation. Sample shows good TL glow curve and for variable UV exposure time maximum TL intensity was found at 20 min UV exposure which is optimized UV exposure time. Sample was studied by photoluminescence emission spectra excited by xenon flash lamp with nearly 360 nm and four prominent peaks found at wavelengths 445, 525, 553, and 565 nm; here the 445 and 565 nm peak were intense as compared to others. From the PL emission spectra, it is concluded that the color tenability of prepared CaY 2 O 4 :Er 3+ was blue-green and it is verified by CIE coordinate. Kinetic parameters of prepared phosphor were calculated by computerized glow curve deconvolution (CGCD) technique.

Controlling the PV array to generate the maximum power at certain environment conditions, the efficiency of the PV generation system could be improved. Using control algorithms, the PV array can operate at the maximum power point. This self-optimization process is referred as Maximum power point tracking (MPPT). A maximum power point tracker (MPPT) is a power electronic DC-DC converter inserted between the PV array and its load to achieve optimum matching. Researchers have studied and developed numerous methods and used many algorithms to track the Maximum power point of PV Module and extract maximum power using MPPT technique. This review article accumulates various algorithms through which MPPT could be attained and assists the researchers to understand the principle of their working. The paper also gives an idea to about less explored DC appliances and their viabilities in existing and proposed DC system.