Photovoltaic (PV) technologies for solar energy conversion represent promising routes to green and renewable energy generation. Despite the fact that relevant PV technologies have being available for more than half a century, the production of solar energy remains costly, largely owing to low power conversion efficiencies of solar cells. The main difficulty in improving the efficiency of PV energy conversion lies in the spectral mismatch between the energy distribution of photons in the incident solar spectrum and the bandgap of a semiconductor material. With the aim of utilizing the infrared region of solar radiation to improve solar cell performance progress has been sought in the field of up & down-conversion for photovoltaic applications. In recent years, luminescent materials, which are capable of converting a broad spectrum of light into photons of a particular wavelength, have been synthesized and used to minimize the losses in the solar-cell-based energy conversion process. In this scenario, we will push recent progress in the development of spectral converters, with a particular emphasis on lanthanide-based upconversion, quantum cutting and down-shifting materials, for PV applications. Particularly, we propose to study the up & down-conversion characteristics of tellurite and germanate based glasses doped with rare earth ions, prepared using the conventional melt quenching technique. These glass matrices will be characterized systematically from their structural (XRD, SEM-EDAX), chemical (FTIR, RAMAN), thermal (TG/DTA/DSC) and spectroscopic (Optical absorption, PLE, PL, excited state lifetime measurements) points of view, besides performing measurements of solar cell quantum efficiency. By using thermal analysis techniques such as TG- DTA and DSC, characteristic temperatures Tg, Tc and Tm will be determined. The glasses will be annealed at suitable temperatures to obtain glass-ceramics. XRD, SEM, TEM, FTIR and Raman studies will be used to investigate the size of the particles and the molecular bonds present in the glass and glass-ceramics. Spectroscopic techniques such as optical absorption, photoluminescence and decay curves will be employed to investigate the excited state dynamics in rare earth doped glass and glass-ceramics. Finally, the obtained results will be correlated and used to optimize the rare earth ions doped glass and glass-ceramics for solar cell applications.
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