Heavy Mn2+-doped near-infrared photon upconversion luminescence in fluoride RbZnF3:Yb3+,Mn2+ guided by dopant distribution simulation

Abstract

Mn²⁺ ions-activated phosphors play a crucial role in modern lighting and display due to their typical tunable single-band visible (VIS) emission characteristics. Herein, besides the conventional VIS emission, a near-infrared (NIR) emission centered at ∼780 nm is presented in heavy Mn²⁺-doped fluoride RbZnF₃:Yb³⁺,Mn²⁺ designed by the dopant-distribution prediction simulation. On varying the dopant (Mn²⁺) concentration, the single-band VIS emission to VIS/NIR dual emission and then to pure NIR photon upconversion (UC) emission was achieved in RbZnF₃:Yb³⁺,Mn²⁺. The density functional theory (DFT) calculations, static and dynamic luminescence analysis, as well as the extended-X-ray absorption fine structure (EXAFS) characterization strongly confirmed that the NIR emission of the Mn²⁺ was from the Mn²⁺–Mn²⁺ dimer induced by Mn²⁺ ions aggregation in RbZnF₃. Further, a ground-state absorption (GSA)/excited state absorption (ESA) NIR UC luminescence mechanism based on the Yb³⁺–Mn²⁺–Mn²⁺ trimer model is proposed. This work provides a new strategy for realizing single-band NIR photon UC emission, and also provides new insights into the rational design of the Mn²⁺ VIS/NIR emission via dopant-distribution prediction.