Enhanced Quantum Efficiency via Co‐substitution in Sr2[MgAl5N7]:Eu2+ for Spectroscopic Applications including Laser Displays with Ultra‐high Luminescence Saturation Threshold

A series of Sr2[Mg1‐xLixAl5‐xSixN7]:0.01Eu2+ (SMAN‐xLS, 0≤x≤0.5) red phosphors were devised and synthesized via the high temperature solid state reaction and the effects of the co‐substitution of [Mg‐Al]5+ by [Li‐Si]5+ on structural and luminescence properties is investigated. With the entry of [Li‐Si]5+ into theSr2[MgAl5N7]:0.01Eu2+ (SMAN) lattice, the substitution of Al3+ by Si4+ shifts the emission peak from 657 nm to 647 nm and reduces the excitation in green region. When the amount of [Li‐Si]5+ co‐substitution is x=0.1, the luminescence intensity and thermal stability of the sample are enhanced, in which the external quantum efficiency is elevated by 49.6%. The increase in lattice rigidity gives rise to higher luminescence intensity, and the introduced trap levels for the compensation of luminescence enhances the thermal stability. Under blue laser excitation, the SMAN‐0.1LS can achieve an ultra‐high luminescence saturation threshold of 52.22W/mm2, which is a breakthrough performance that has enormous potential for application in high‐power laser display light sources. By measuring the pressure‐dependent luminescence of SMAN‐0.1LS, the emission peak can be shifted from 650 nm to 702 nm with the increase of pressure, and the sensitivity dλ/dP is 5.07 nm/GPa, which is indicative of the potential application of this system as an optical pressure sensor.