Efficient Near-Infrared Quantum Cutting in Y₂O₃ Codoped with Ho³⁺,Yb³⁺ Phosphor Synthesized by Solution Route

A series of Ho3+/Yb3+-codoped cubic Y2O3 nanoparticles were prepared by complex based precursor solution method. The phase purity of the samples was characterized by X-ray diffraction. Crystal structure of Y2O3:Ho3+(1 mol %), Yb3+ (30 mol %) phosphor was refined using Rietveld refinement method. The energy-transfer (ET) phenomenon between Ho3+ ions and Yb3+ ions was verified by steady-state as well as time resolved photoluminescence (PL) spectroscopy measurements. An efficient green emission has been observed upon excitation by 449 nm, which decreases monotonously with increasing Yb3+ concentration. Beyond that, the decay curves were also measured to certify the existence of the ET process. The down conversion phenomena appeared when the samples were excited by 449 nm wavelengths corresponding to the transition of Ho3+:5I8→5G6/5F1. On the basis of the analysis of the relationship between the initial transfer rate of Ho3+: 5F3 level and the Yb3+ doping concentration, it indicates that the ET from 5F3 state of Ho3+ ions to 2F5/2 state of Yb3+ ions is mainly through at wo step ET process, not the long-accepted cooperative ET process. In addition, a 97% ET efficiency and 197% quantum cutting can be achieved in Y2O3:1% Ho3+, 20% Yb3+. The current research indicates that Y2O3:Ho3+/Yb3+is a promising material to improve conversion efficiency of crystalline silicon solar cell.