Study On Preparation,optical Properties And Application Of C12A7:Yb³⁺/Tm³⁺ Upconverting Materials

With the unrestrained exploitation and use,fossil energy is in danger of being depleted,it is urgent to develop and use renewable clean energy.Solar energy is widely distribute,and inexhaustible,so it has a huge development and application prospects.At present,the main way to develop solar energy is to use solar cells for photoelectric conversion.Among many solar cells,dye-sensitized solar cells?DSSC?have become the focus of research all over the world due to its green environment,low cost,simple process and high photoelectric conversion efficiency.However,due to the limitation of the band gap width of the photoanode and the response range of the photosensitive dyes to the sunlight,DSSC can only absorb the visible light in the wavelength range of 300-800nm,so the infrared light,which takes up 43%of the sunlight,cannot be absorbed and utilized.Therefore,it is of great significance to improve the utilization rate of DSSC to sunlight by doping rare earth ions with on-conversion luminescent materials to convert infrared light into absorbable visible light by using anti-stokes effect in the photoanode.In this thesis,the up-conversion luminescent material C12A7:Yb³⁺/Tm³⁺was synthesized by hydrothermal method using 12Ca O?7Al₂O₃?C12A7?as the host material,doped with rare earth ions ytterbium(Yb³⁺)and thulium(Tm³⁺).By changing the hydrothermal time and solvent ratio,we obtained the patteren and porous square C12A7:Yb³⁺/Tm³⁺.All samples can emit blue and red up-conversion fluorescence under 980nm laser excitation.Apply the prepared porous block C12A7:Yb³⁺/Tm³⁺to DSSC photoanode,However,due to the poor conductivity of the up-converting luminescent material,and the energy band structure is also very mismatched with the dye molecule,resulting in greater internal electron transmission resistance of the battery,the modified DSSC photoelectric conversion efficiency is 5.57%,compared to the control group the efficiency is reduced by 18.6%.In order to optimize the structure of DSSC photoanode,we applied anatase Ti O₂:Yb³⁺/Tm³⁺prepared by hydrothermal method,which not only broadened the response range of DSSC to sunlight,but also had better dye adsorption capacity.Effect,the photoelectric conversion efficiency increased to 7.41%,compared with the control group,the efficiency increased by 8.3%.The core-shell structure of the porous block C12A7:Yb³⁺/Tm³⁺was prepared and applied to the DSSC photoanode.With TTIP as the titanium source,the surface of C12A7:Yb³⁺/Tm³⁺was coated with Ti O₂.Due to excessive TTIP,the proportion of C12A7:Yb³⁺/Tm³⁺@Ti O₂ in the synthesized powder material was less,and the proportion of Ti O₂ pellets was larger.Therefore,the up-conversion luminescence performance of the composite prepared by coating experiment was worse,but the excess Ti O₂ pellets could absorb dyes well.When the TTIP dosage is 2ml,the dye-sensitized solar cell prepared has the best performance,and the photoelectric conversion efficiency is 7.15%,which is 4.5%higher than that of the control group.Using the sol-gel method and hydrothermal method with double core-shell structure C12A7:Yb³⁺/Tm³⁺@Si O₂@Ti O₂,the preparation of Si O₂ shell solves the conversion luminescence materials on the introduction of the electron in the problem of migration of battery internal resistance increases,further improve the efficiency of the DSSC photoelectric conversion,TEOS dosage of 0.1 ml,The prepared dye-sensitized solar energy has the best function,and the battery efficiency is 9.02%,compared with the control group,the efficiency increased by 31.9%.