Upconversion luminescence of La4Ti9O24: Er–Yb phosphor with high green color purity

Upconversion materials with high green color purity are considered to have greater potential in the development and manufacturing of modern optoelectronic devices. However, the generation of high green color purity in Er3+-Yb3+ ions doped upconversion materials is usually a great challenge. Herein, we develop a series of Er3+ singly doped, and Er3+-Yb3+ co-doped La4Ti9O24 phosphors with high green color purity under 980 nm irradiation. The green emission of the phosphor was not changed by increasing Yb3+ concentrations, and the material exhibited excellent color purity. We found that low phonon energy and layered structure are the main causes of high green color purity by analyzing Raman spectrum and crystal structure. Based on CIE chromaticity estimates from 1931 in terms of coordinates, dominant wavelength, and color purity, La4Ti9O24: 3 mol% Er3+ and La4Ti9O24: 3 mol% Er3+-16 mol% Yb3+ presents the color purity of 95.14% and 96.04%, respectively.