Unraveling the Luminescence Quenching of Phosphors under High-Power-Density Excitation

Abstract

Laser-driven phosphor-converted white light sources have received great attention for next-generation high-brightness lighting and display technologies. However, luminescence quenching of down-conversion phosphors under high-power-density excitation severely restricts the luminous efficacy and light output of laser-driven lighting devices. Till now, the quenching mechanism, once assigned to thermal quenching, is still argued, making it difficult to select appropriate laser phosphors. In this work, we identify the optical excitation quenching (a non-thermal quenching effect) rather than thermal quenching that dominates the luminescence loss of Ce3+- and Eu2+-doped phosphors under high-power-density excitation. The optical excitation quenching is mainly caused by the energy-transfer upconversion (ETU), and the quenching rate is greatly dependent on the decay time of phosphors, evidenced by combining the experimental data with theoretical models. A critical parameter, named as optical excitation quenching behavior, is finally proposed to screen laser phosphors.