Photoluminescence of Eu³⁺-doped glasses with Cu²⁺ impurities

Abstract Glasses activated with Eu³⁺ ions are attractive as luminescent materials for various photonic applications. Co-doping with copper has been proposed for enhancing material optical properties, but the quenching effect of Cu²⁺ impurities on Eu³⁺ emission in glass remains largely unexplored. In this work, Eu₂O₃/CuO-containing barium-phosphate glasses have been prepared by the melt-quench method, and the Eu³⁺ photoluminescence (PL) quenching resulting from Eu³⁺ → Cu²⁺ energy transfer was evaluated. Optical absorption spectroscopy showed that with the increase in CuO concentration the Cu²⁺ absorption band resonant with Eu³⁺ emission (e.g. ⁵D₀ → ⁷F₂ transition around 615 nm) developed steadily. As a result, Eu³⁺ PL was progressively quenched. Evaluation of the quenching constants as a function of temperature in the 298-673 K range showed differences basically within experimental error, consistent with a resonant transfer and lack of phonon-assisted processes. Moreover, analysis of the Eu³⁺ emission decay dynamics revealed a strong correlation between the decay rates and Cu²⁺ impurity levels. Results imply that for practical applications the levels of Cu²⁺ in Eu³⁺/Cu⁺-activated glasses should be reduced if not removed as these will significantly limit device efficiency.