Design of the YAG:Ce3+ phosphor in tellurite-germanate glass with high luminous efficiency for laser lighting

Abstract

The main focus of laser lighting research has been on perfectly combining fluorescent conversion materials with laser light sources to improve luminous efficiency (LE). In this paper, the high refractive index, high transmittance and low sintering temperature of tellurite glass is combined with the thermal stability and mechanical strength of germanate glass，which is innovatively used as a matrix for phosphor-in-glass (PiG). The use of high valent ions as modifiers reduces the diffusion and mobility of ions to reduce the erosion of phosphors and protect the luminescent performance of phosphors. By changing Ge/Te ratio, the glass maintains 80% transmittance, and the refractive index decreases from 1.97 to 1.83 matching that of the YAG phosphor. The increase in GeO2 improves the thermal stability and mechanical strength of the glass, thereby improving the fluorescence intensity (approximately 1.6%) at 473 K and the luminous flux by up to 12.8%. The best PiG sample had a LE of 230 lm/W and excellent internal quantum efficiency (IQE) of 85.3%, achieving high levels of luminescence. Adding different phosphor contents can achieve the role of adjusting the correlated color temperature (4500–6000 K), and the color coordinates (0.322, 0.330) are close to the ideal white light. These results show that tellurite-germanate glass can be used as a good carrier for fluorescence conversion materials, which brings a new direction for the exploration of glass matrix.