UC San Diego

Phosphor-converted white light-emitting diodes (pc-WLEDs) have been widely adopted for next-generation solid-state lighting mainly. However, our understanding of thermal-quenching (TQ), i.e., the loss of photoluminescence (PL) intensity with increase of temperature, remains incomplete, with several competing theories. In this work, we demonstrate the application of ab-initio molecular dynamics (AIMD) simulations as a novel approach to investigate the effect of temperature on Eu2+/Ce3+ LE. A statistical analysis of the activator LE is extracted from the atomic trajectories from AIMD at multiple temperatures revealing a clear relationship between the temperature-dependent activator LE, and the experimentally measured TQ in numerous well-known phosphor compounds. We have found that phosphors with low TQ show a small variability in their activator’s LE distribution within the operating temperature range. We propose a model where the activator LE fluctuations due to temperature lead to changes in the crystal field splitting around the activator, which in turn have a consequence on the photoionization barrier and TQ behavior. Finally, we propose structural descriptors based on these observations that can be used to rapidly screen novel materials for high quantum efficiency phosphors with excellent TQ resistance.