Anti-Thermal Quenching Phosphors based on Metal Halides

TL;DR

This paper reviews recent progress in metal halide phosphors that resist thermal quenching, highlighting their mechanisms, advantages, and potential for high-temperature applications, emphasizing their promising low-temperature synthesis and high PLQYs.

Contribution

It provides a comprehensive overview of anti-thermal quenching metal halide phosphors from 2017 onward, discussing their mechanisms, applications, and fundamental properties.

Findings

Metal halides show promising anti-TQ properties despite soft lattices.

Low synthesis temperatures and high PLQYs make metal halides attractive for high-temperature applications.

Understanding anti-TQ mechanisms in metal halides is an emerging research area.

Abstract

Thermal quenching (TQ) generally occurs in phosphors and is ascribed to the activation of non-radiative transitions at elevated temperatures. This effect limits the use of most phosphors in high-power/high-temperature applications, such as outdoor lighting and laser systems. To achieve anti-TQ properties, structural design of phosphors is required. This usually follows two guidelines: (1) increasing lattice rigidity to minimize thermal expansion; (2) converting thermal energy into radiative transitions to compensate for the non-radiative losses. While metal oxides and metal nitrides dominate the field of commercial anti-TQ phosphors, metal halides - despite their inherently soft lattices - have shown remarkable progress as anti-TQ phosphors in recent years. Here, we review the advances in anti-TQ metal halides (covering the time span from 2017, when first reports have appeared, till today) and discuss their mechanisms and applications. We argue that the low synthesis temperatures of metal halides and their high photoluminescence quantum yields (PLQYs) make them promising candidates as anti-TQ phosphors. Furthermore, since the rich optical-physical processes underlying the anti-TQ effect in soft-lattice in metal halides are only now beginning to be unraveled, this creates opportunities for many fundamental investigations.