Lanthanide-Doped KMgF<sub>3</sub> Upconversion Nanoparticles for Photon Avalanche Luminescence with Giant Nonlinearities.

Zhang, Meiran; Huang, Ping; Zheng, Wei; Song, Xiaorong; Shang, Xiaoying; Zhang, Wen; Yang, Dengfeng; Yi, Xiaodong et al. · Nano Lett · 2023

basic_science · Level V

Where this comes from

Abstract

Lanthanide (Ln<sup>3+</sup>)-doped photon avalanche (PA) upconversion nanoparticles (UCNPs) have great prospects in many advanced technologies; however, realizing efficient PA luminescence in Ln<sup>3+</sup>-doped UCNPs remains challenging due to the deleterious surface and lattice quenching effect. Herein, we report a unique strategy based on the pyrolysis of KHF<sub>2</sub> for the controlled synthesis of aliovalent Ln<sup>3+</sup>-doped KMgF<sub>3</sub> UCNPs, which can effectively protect Ln<sup>3+</sup> from luminescence quenching by surface and internal OH<sup>-</sup> defects and thereby boost upconversion luminescence. This enables us to realize efficient PA luminescence from Tm<sup>3+</sup> at 802 nm in KMgF<sub>3</sub>: Tm<sup>3+</sup> UCNPs upon 1064 nm excitation, with a giant nonlinearity of ∼27, a PA response time of 281 ms, and an excitation threshold of 16.6 kW cm<sup>-2</sup>. This work may open up a new avenue for exploring highly nonlinear PA luminescence through aliovalent Ln<sup>3+</sup> doping and crystal lattice engineering toward diverse emerging applications.