Preparation Of Rare Earth Luminescent Materials And Its Application In DSSCs

With the increasingly severe status of energy and environment,the development and utilization of new energy becomes more critical.As a clean and renewable future energy,Solar energy is particularly important in the current situation.Among the solar cells,Dye-sensitized solar cell is one of the novel types,which have attracted great attention owing to many favorable advantages in comparison with conventional silicon-based solar cell,such as,low cost,simple fabrication process,high theoretical efficiency and other advantages.In past several years,global scientific and technological workers have carried out a lot of research work.However,its efficiency and stability is relatively lower compared to the silicon-based solar cells.The reason for the low efficiency of photoelectric conversion is mainly because there exists a lot of energy loss in the photoelectric conversion process.On the one hand,the absorption range of dyes?such as N719,400?600nm?is mainly in the visible light band,which means the ultraviolet and infrared sunlight cannot be absorped.On the other hand,photoelectric conversion process exists charge recombination.In this paper,aiming at the limited absorption range of N719 dye,we proposed to find suitable luminescent materials to solve the problem of spectral mismatch,so as to broaden the photoabsorption region and improve the efficiency of solar cells.For this goal,this paper has done the following work:1.Ce³⁺ and Tb³⁺ codoped CaF₂ were prepared by high temperature solid-state method.The emission spectrum is composed of multiple band emission peaks,which are located at 487,543,585,and 621 nm,respectively,belonging to Tb³⁺ 5D4?7Fn?n = 6,5,4,3?transition emission.Among these emission peaks,the strongest peak is 543nm green light emission,which matches well to N719 dye absorption range.The optimum doping concentrations of Ce³⁺ and Tb³⁺ were 5 mol%and 3 mol%,respectively,and the energy transfer efficiency of Ce³⁺->Tb³⁺is 33.5%.Use this material to modify the TiO2 anode and then assemble solar cells.The photoelectric characterizations showed that the short circuit current density and photoelectric conversion efficiency were greatly improved to 11.224 mA · cm-2 and 4.90%,respectively.2.The CaF₂:Eu²⁺,Tb³⁺ luminescent materials were synthesized by high temperature solid-phase method.The excitation spectra obtained at the wavelength of 543nm includes the band?320-415nm?from near ultraviolet to violet light,belonging to Eu²⁺:5d?4f level transition.Under the excitation of 398nm ultraviolet light,the emission spectrum of sample behaves as both 429nm?4f?5d?blue light emission of Eu²⁺and 543nm?5D4?F5?green light emission of Tb³⁺,indicating that there exists energy transfer from Eu²⁺ to Tb³⁺.The optimum dopant concentration of Eu²⁺ and Tb³⁺ were both 5mol%.At this time,the strongest green light emission was obtained,and energy transfer efficiency of Eu²⁺?Tb³⁺ is 55.9%.The results of J-V analysis show that the short-circuit current density is 12.252 mA·crm-2,and the photoelectric conversion efficiency is 5.16%,which raised by 43.3%compared to cells fabricated by TiO2 anodes.3.The perovskite rare earth luminescent material Ca_1-1.5xTb_xZrO₃ was synthesized by high temperature solid-phase method.The excitation spectrum of the sample present as a band-shaped excitation peak,the center of which is 289nm,belonging to the semiconductor Zr4+-O2-?Zr4+-O-electron transition excitation.The emission spectra were obtained at 289 nm UV excitation,in which the emission peaks 487 and 543nm were both typical peaks of of Tb³⁺.When the dopant concentration of Tb³⁺ is 4mol%,the luminous intensity of the sample is the strongest.The solar battery testing results show that Ca_1-1.5xTb_xZrO₃ havs improved the short-circuit current density and photoelectric conversion efficiency of the battery,reaching 11.881 mA·cm-2 and 4.89%,respectively.