Synthesis And Properties Of Oxide (Oxynitride) Conversion- Spectral Materials For Solar Cells

Solar energy is a key issue in the field of new energy study owing to its obvious advantages, such as abundant, green, environmentally-friendly and wide-distributed characters, compared to others. The spectral mismatch between the emitted spectrum of the sunlight and the absorption spectrum of the band gap originated from the silicon-based solar cell lead to the serious energy loss. In order to resolve this problem, the application of the wavelength-conversion materials is one of the best choice to enhance the efficiency of the silicon-based solar cell. Among them, rare earth-doped spectral conversion materials become the hot issue for the wavelength-conversion. In this thesis, we firstly analyzed the mechanism of the energy loss of the solar cell originated from the spectral mismatch, and then summarized the recent advances of rare earth doped luminescence materials used in the spectral conversion for solar cell, finally proposed the present research work on the exploration of the novel red, deep red and near infrared luminescence materials for spectral conversion in solar cell. The synthesis, structure and luminescence properties of different wavelength-conversion materials have been investigated, and the potential application have been studied from the optical properties. The main research contents are listed below:(1) Ca(2-x)BaxLaNbO6:Eu3+,Yb3+ were prepared by solid-statereaction. The structural transitions depending on Ca/Ba ratios from Ca2LaNbO6 to Ba2LaNbO6 were studied via X-ray diffraction, and further probed by the characteristic red emission of Eu3+. By the energy transfer from Eu3+ to Yb3+ in Ca2LaNbO6, a new type of spectral conversion material that can convert the ultraviolet (UV) and visible (vis) absorption into near-infrared emission obtained.(2) LaMgAl11O19:Cr3+,Nd3+ were prepared by solid-statereaction at high temperature. The energy transfer process from Cr3+ to Nd3+ was confirmed, the critical radius as well as the transfer efficiency was calculated. The absorption of LaMgAl11O19:Cr3+ spaned the spectral range of 350-650 nm. This enabled broadband sensitization of Nd3+ around 1055 nm. So the Cr3+,Nd3+ co-doped LaMgAl11O19 were expected to be developed as spectral converiosn materials for silicon solar cells.(3) Y2Si3O3N4:Ce3+,Tb3+,Yb3+ were prepared by solid-statereaction at high temperature and pressure. The energy transfer process from Ce3+ to Tb3+ was confirmed, the critical radius as well as the transfer efficiency was calculated. The charge transfer (CT) band from N3--Yb3+ in Y2Si3O3N4 was observed in an unusually region from UV to vis. Excitation of this CT band resulted in f-f emission of Yb3+ around 980 nm, which could make Yb3+ doped Y2Si3O3N4 suitable for application as a spectral conversion material.