Ce³⁺/Yb³⁺ Codoped Fluoride Near-infrared Quantum Cutting Property And Applied On Solar Cell

This research mainly worked on the rare-earth ions doped luminescent materials in order to modify the solar spectrum and improve the solar efficiency.Under the ultraviolet?UV?light excitation,the material efficiently convert one higher energy photon to two highly responsive photons.The emission band is located at near infrared?NIR?region,which is just matched the spectral response of Si band gap.This scheme has the practicability for enhancing the photovoltaic performance of solar cells efficiently.The cerium fluoride CeF₃ material was formed by a facile and effective hydrothermal approach.Its morphology structure and luminescence property was controlled by changing the addition of complexing agent,pH and reaction time.The best morphology of CeF₃ was formed under the EDTA = 2 mmol,pH = 9,t = 5 h and 160?.They all in good uniform spherical shape with well dispersion,and the size was around 500 nm.Furthermore,in the fluorescence?PL?spectra,under the UV excitation,the strongest emission was peaking around 300 nm,which matched the transfer of 4f and 5d energy levels of Ce³⁺ ions.In the Yb³⁺ ions doped CeF₃ material,there was an emission at the NIR region because of the energy transfer process between Ce³⁺ions and Yb³⁺ions.Highly uniform and well dispersed CaF₂ hollow spheres codoped with Ce³⁺ and Yb³⁺ions were synthesized based on Ostwald ripening mechanism,which size was around 450 nm with a shell thickness of 100 nm.The emission spectra of CaF₂:0.5%Ce³⁺ phosphor has the strongest emission bands located at 317 nm and 336 nm,originating from the 5D0?2F7/2 and 5D0?+2F5/2 transition of Ce³⁺ respectively.Meanwhile,in the CaF₂:0.5%Ce³⁺-Yb³⁺ emission centered at 965 nm and 1027 nm own to the 2F5/2 to 2F7/2 transition of Yb³⁺ energy level.The emission intensity is mainly attributed to the doping content of Yb³⁺ and their predominant vibration frequencies available in the host.The decreasing lifetime of Ce³⁺ ions suggests that the energy from Ce³⁺ to Yb³⁺ is resonant energy transfer.Moreover,the prepared effective wavelength conversion material was proposed to enhance the photovoltaic efficiency of silicon solar cells via introducing an anti-reflection?AR?and wavelength conversion bi-functional film.All of the functional films have a better performance than pure SiO2 film and glass.The best addition of CeF₃:Yb³⁺ in the AR coating film is 0.02 g,but it is 0.05g in the CaF₂:Ce³⁺-Yb³⁺ AR coating film.As a proof-of-concept application,the renewed AR coating films were used to test the standard monocrystalline silicon solar cell photoelectric conversion properties.CaF₂:Ce³⁺-Yb³⁺ AR coating film effectively improved the photoelectric conversion efficiency better than other samples.This project provides a good practical solution for enhancing the photoelectric performance of the solar cells.