Near-infrared luminescence and energy transfer processes in LaOF:Nd3+, Yb3+

Abstract

Nd³⁺ and Yb³⁺ singly and codoped samples of LaOF were prepared by a hydrothermal synthesis method and the phase purity of samples was examined by X-ray powder diffraction. The Yb³⁺ concentration dependence of luminescence and decay times of LaOF:Nd³⁺, Yb³⁺ were investigated. Cross-relaxation energy transfer from Nd³⁺ (⁴D_3/2 → ⁴G_5/2) to Yb³⁺ (²F_7/2 → ²F_5/2) was confirmed not only based on the excitation spectra, but also by the decay properties of the Nd^{3+ 4}D_3/2 state. However, the dominant process was multi-phonon relaxation from Nd³⁺ higher levels to ⁴F_3/2, followed by energy transfer to Yb^{3+ 2}F_5/2. In addition, host energy transfer to Yb³⁺ and back energy transfer from Yb³⁺ (²F_5/2 → ²F_7/2) to Nd³⁺ (⁴I_9/2 → ⁴F_3/2) were also revealed. The present study could be rewarding in the design of efficient spectral converters applied in silicon-based solar cells.