Sunlight-activated Eu3+-doped CaNaSb2O6F yellow-orange long-persistence luminescence material

Abstract

Persistent luminescence (PersL) materials, especially sunlight excitable warm color (550–660 nm) PersL materials, have great practical value in information storage, emergency lighting and displays, and in vivo alternating current LED lamps. But up to now, designing and developing efficient sunlight-activated warm color PersL materials has faced huge challenges. Here, we present a novel Eu³⁺-doped CaNaSb₂O₆F yellow-orange PersL phosphor. The charge transfer transition of the phosphor occurs in the near UV region (peaking at 336 nm), which enables the phosphors to be excited effectively under the irradiation of natural sunlight or a low-energy mercury lamp (365 nm UV light) and to exhibit excellent yellow-orange (560–700 nm) PersL. The effective warm-color emission is dominated by the dual emission at 561 and 639 nm originating from the ⁵D₁ → ⁷F₂ and ⁵D₀ → ⁷F₃ transitions of Eu³⁺ ions in the CaNaSb₂O₆F lattice with a symmetrical coordination environment. Impressively, this new phosphor can be recharged rapidly and effectively in various conditions using natural sunlight, which lays a foundation for the long-term stable operation of phosphors in practical applications. Based on the study of thermal luminescence and defects, a feasible hole detrapping PersL mechanism was proposed. This study opens up a new avenue for research into improved sunlight-excited warm color PersL materials in the future.