Wide-band excited and deep-red sensitized Mn2+ emission from an NaSrSc(BO3)2:Eu2+,Mn2+ phosphor with vanished Eu2+ emission

Abstract

It is of great importance to develop new broadband red phosphors since they have possible applications like plant cultivation, indoor lighting and non-destructive sensing. Herein, we report a series of Eu²⁺, Mn²⁺ activated NaSrSc(BO₃)₂ phosphors via a conventional solid-state reaction route. It has been found that both Mn²⁺ and Eu²⁺ solo-doped NaSrSc(BO₃)₂ show weak or no luminescence, while Eu²⁺, Mn²⁺ co-doped NaSrSc(BO₃)₂ exhibits wide-band absorption and intense deep-red emission at 680 nm with color purity of 89%. Analysis of the absorption, excitation and emission spectra of Eu²⁺, Mn²⁺ solo- and co-doped NaSrSc(BO₃)₂ indicates that this deep-red broadband emission originates from Eu²⁺ sensitization of the octahedron Mn^{2+ 4}T₁–⁶A₁ transition. It was found that the photoionization process led by energetic similarity of the host band-gap and the Eu²⁺ lowest 5d excited state was mainly responsible for the vanished luminescence of Eu²⁺. The values of internal quantum efficiency (IQE) and absorption efficiency (AE) for the optimal NSSO:0.007Eu²⁺,0.05Mn²⁺ sample are 24.5% and 61.8%, respectively. This work could provide new insights into exploring novel Mn-activated deep-red luminescent materials.