Jiangxi University of Science and Technology Institute of Materials and Metallurgy Chemistry Institute of Advanced Rare Earth Luminescent Materials and Devices Research Institute has made important progress in the screen printing technology preparation and luminous properties of lead-free / tellurium-based YAG glass ceramics for high-power white LEDs. Published in the domain authoritative journal "Journal of the European Ceramic Society". The first author of the paper is Dr. Xia Libin from the Institute of Advanced Rare Earth Luminescent Materials and Devices of the Department of Materials Metallurgy and Chemistry, and Professor Liang Tongxiang of the Department of Research and You Weixiong of the Institute are the co-corresponding authors of the paper.
White LEDs have been widely used in general lighting, indicator displays, backlights, automotive headlights and other fields in recent years due to their long life, energy saving, and environmental protection. However, current commercial white LEDs suffer from poor thermal stability due to organic packaging and low color rendering due to lack of red light, which limits their applications in the field of high power and high quality lighting. In this paper, the research team prepared a YAG glass ceramic containing no lead and tellurium, using rare earth Eu3 + red light glass as a carrier and simple screen printing technology. The ceramic can effectively replace the organic packaging of the existing LED, which not only greatly improves the thermal stability of the device, but also makes up for the lack of red light in the LED to a certain extent. After compounding with the blue light chip, it achieves a good warm white light. emission. The research will provide a reliable theoretical basis and practical reference for the preparation and development of fluorescent glass ceramics for high-power high-efficiency white LEDs.
Aiming at the problems of high cost, environmental pollution, and insufficient red light caused by the widespread use of tellurium and lead acid glass as substrates in the current research on YAG glass ceramics, the research team first used rare earth Eu3 + doped borobismuth glass as a substrate and adopted YAG glass-ceramics were prepared by a simple screen printing technique. The behavior of YAG phosphors in glass-ceramics by glass substrate erosion and light emission were studied using DSC, SEM / EDS, XRD, fluorescence lifetime, absorption spectrum, and excitation / emission spectrum. The energy transfer between ions, the change law of the luminous performance of glass ceramics with temperature, and the comprehensive photoelectric performance of white LED devices assembled with glass ceramics, etc., have resulted in a low cost, pollution-free, high thermal stability and high luminous performance. Glass ceramics for power white LEDs.
In this work, the research team used rare earth Eu3 + doped red light glass as a matrix carrier (relatively high melting point), and printed YAG phosphor and low melting point borobismuth acid glass powder on the surface of the matrix glass by screen printing technology, and prepared a good YAG glass-ceramics for white LEDs with luminous properties. At the sintering temperature of 570 ° C, the YAG phosphors in the glass-ceramic samples were not substantially attacked by the glass matrix; the energy transfer between the Eu3 + and Ce3 + luminescent ions was effectively suppressed due to the spatial separation of the crystalline / amorphous phases. The quantum efficiency of the prepared YAG glass ceramic is as high as 85.06%, which is only 5% lower than that of the YAG raw material; the thermal stability is up to 85.01% at 150 ° C, which is much higher than the value of organic packaging in existing commercial white LEDs; glass ceramics After the blue LED chip is assembled, the luminous performance index of the device is 117.2 lm / W, color temperature 5859 K, and color rendering index 77.2. Compared with existing commercial LED parameters, the lumen efficiency is equivalent, but the color temperature and color rendering index are significantly optimized. The above research indicates that the YAG glass ceramic prepared by this work is expected to be applied to the field of high-power white LED lighting due to its advantages such as low cost, no pollution, high thermal stability, and good light emitting performance.