Efficient Cu⁺ to Ho³⁺ Energy Transfer in Highly CuO/SnO Co-doped Phosphate Glass

Glasses activated with Cu⁺ ions and rare-earths are attractive materials for luminescent down-shifting (LDS) in solar cells. This calls for investigating on fundamental interactions between dopants aiming to understand the factors underpinning resulting optical properties. Accordingly, this Communication reports for the first time on the determination of Cu⁺ → Ho³⁺ energy transfer efficiencies in melt-quenched phosphate glass containing holmium(III) together with a high concentration of Cu⁺ ions obtained through CuO/SnO co-doping. Material characterization was carried out by UV/Vis absorption and photoluminescence spectroscopy including a Cu⁺ emission decay assessment. The data revealed suppressed Cu⁺ visible emission and reduced lifetimes in the presence of Ho³⁺ ions consistent with an efficient Cu⁺ → Ho³⁺ energy transfer, most significant for Cu⁺ emission in resonance with Ho³⁺ absorption. The findings point to Cu⁺ ions being efficient energy donors to Ho³⁺ which may have implications for the development of glasses for LDS and laser materials as well.