Cooperative Down-Conversion Luminescence in $ \hbox{Tb}^{3+}/ \hbox{Yb}^{3+}$ Co-Doped $\hbox{LiYF}_{4}$ Single Crystals

Li Fu,Baojiu Chen,Haochuan Jiang,Yanmin Dong,Haiping Xia,Shanshan Li

doi:10.1109/jphot.2014.2300495

Abstract

Cooperative down-conversion (DC) with emission of two near-infrared photons for each blue photon absorbed was achieved in Tb3+/Yb3+ co-doped yttrium lithium fluoride single crystals grown by an improved Bridgman method. The luminescent properties of the crystals were investigated through photoluminescence excitation, emission spectra, and decay curves. With the excitation of Tb3+ ion by a 486 nm light, emission between 980 and 1030 nm from the Yb3+:2F5/2 → 2F7/2 transition was observed, and this emission originated from the DC between Tb3+ and Yb3+ ions. The energy transfer processes are studied based on the Inokuti-Hirayama's model, and the interaction between Tb3+ and Yb3+ is confirmed to be electric dipole-dipole. The large quantum cutting efficiency approaches up to 166.7% for 0.32 mol% of Tb3+ and 7.98 mol% of Yb3+ co-doped LiYF4, which is potentially used as a DC layer in silicon-based solar cells.

Highlights

Nowadays there is a great interest in solar power due to its green, abundance and renewability [1]
Recent works on InGaAsN-containing quantum wells grown on GaAs have led to high performance and very low threshold lasers [5]–[8], and these advances in dilute-nitride materials had led to recent promising results with more than 43.5% solar conversion efficiency [9]
More Recently, we have presented experimental evidences for a cooperative energy transfer (ET) from Pr3þ to two Yb3þ ions in the Pr3þ=Yb3þ co-doped LiYF4 single crystal for potential application in solar cells [1]

Summary

Introduction

Nowadays there is a great interest in solar power due to its green, abundance and renewability [1]. Cooperative down-conversion has attracted much more attention for its potential applications in the fields of solar cells, plasma display et al This method is based on the principle that twoenergy near-infrared (NIR) photons were generated when each incident high-energy ultraviolet (UV) or visible (VIS) photon was absorbed By such spectral modification, the energy conversion rate of crystal silicon solar cell can be enhanced significantly because the most effective absorption band of crystalline Si for sunlight is around near-infrared wavelength of 1000 nm. LiYF4 crystal doped with rare-earth ions has been proven to be an efficient all-solid-state laser media because of its good chemical durability and thermal stability, high optical transparency in a wide wavelength range from infrared to ultraviolet, and lower phonon energy. The cooperative ET from Tb3þ to Yb3þ ions in the Tb3þ=Yb3þ co-doped LiYF4 single crystal will be discussed

Experimental Details

Results and Discussion

Conclusion