Luminescence Properties And Energy Transfer From Ho³⁺to Yb³⁺in NaLuF₄:Ho³⁺, Yb³⁺

It is expected to improve the conversion efficiency of silicon solar cells by modifying solar light spectrum use rare earth conversion material. Due to lower phonon energy and the good stable of Rare earth fluoride, it is a high-quality matrix material. In this paper, we investigated the spectral properties and energy transfer of Ho3+ single doped and Ho3+/Yb3+ co-doped NaLuF4.The main researches are as follows:(1)The powder samples of β-NaLuF4:1%Ho3+, x%Yb3+(x=0,1,6,10,20) were synthesized by hydrothermal method. The good crystallinity was proved by XRD technique. The PLE spectra of sample monitored at emission lights of Ho3+(542 nm) and Yb3+(984 nm) are overlap well with each other. Yb3+ infrared emission are observed in Ho3+/Yb3+ co-doped sample under 360 and 448 nm excitation, respectively. The above phenomena show energy transfer from Ho3+ to Yb3+. The variation tendency of build-up in the beginning of the decay curves of the Yb3+ is consistent with the correlative energy level decay curve of the Ho3+ ion. It was further prove exist energy transfer from Ho3+ to Yb3+.(2) We analyzed the energy transfer process from Ho3+ to Yb3+ by energy levels decay curve of Ho3+,it indicate s-NIR emission of Yb3+can be obtained via CET and cross relaxation process, under 448 nm excitation.(3)It indicates two-step energy transfer from Ho3+(5G4â†'5F5) to Yb3+(2F7/2â†'2F5/2 and from Ho3+(5F5â†'5I7) to Yb3+(2F7/2â†'2F5/2) via the PLE of sample monitored at emission lights of Ho3+(542 nm) with various Yb3+ion concentration and the decay curve of Ho3+(5Fs),under 360 nm excitation.(4) Decay curves with various Yb3+ concentration were fitted by two-step energy transfer model at 360 nm excitation, it show Ho3+ can transfer energy to Yb3+ via 5G4â†'5F5. It was further proof energy transfer from Ho3+ to Yb3+ may via two step energy transfer under 360 nm excitation.