Progress Analysis of LED in Green Phosphor Research

LED-based solid-state lighting devices with high efficiency, energy saving, environmental protection, etc., is considered to replace the traditional incandescent, fluorescent lamp next-generation lighting source. Phosphor with wavelength conversion function, in determining the white performance such as color rendering index, color temperature, efficiency plays an important role, is one of the key materials for white LED lighting devices.

In recent years, many promising fluorescent phosphors have been developed, of which nitride has drawn much attention due to its high chemical and thermal stability. White LED work chip temperature is about 150 ℃, at this temperature, the luminous efficiency of nitride phosphors can usually be maintained at room temperature efficiency of 80-90%, showing better thermal stability. However, the synthesis conditions of nitrides are relatively harsh. Higher nitrogen or ammonia pressure (100 MPa), higher temperature (1400-2000 ° C.) and longer reaction time are required in the preparation process, and these factors lead to the cost of nitride phosphors High. Therefore, the development of new phosphors with higher efficiency and better thermal stability is still the goal pursued by people.

Liu Yongfu, Jiang Jun and Jiang Hao-chuan, researchers at Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, adopted the solid-phase reaction method at relatively low reaction temperature (1200-1400 ℃) and short reaction time (2-4h) A Ba9Lu2Si6O24: Ce3 + orthosilicate green phosphor was prepared. The optimal excitation peak of the phosphor is at 400 nm, which matches with the emission wavelength of ultraviolet (UV) chip. Under the excitation of 400nm light source, the emission peak of the green phosphor is at 490nm, the FWHM is 120nm, the fluorescence quantum efficiency at room temperature is 82%, and reaches the level of most of the nitride (the quantum efficiency of the nitride fluorescent material is usually 70-90% ). At 160 ℃, its fluorescence quantum efficiency can be maintained at 94% at room temperature, indicating that the green phosphor has better thermal stability than most nitride phosphors, which is mainly due to the formation of LuO6 octahedra and SiO4 tetrahedra Of the total vertex of the SiO4-LuO6-SiO4 rigid connection. Meanwhile, the raw materials for preparing the green phosphor are easy to obtain and the synthesis process is simple, which greatly reduces the product cost, which provides a competitive material selection for the application of the white LED lighting device based on the UV-LED chip.

LED green phosphor research progress

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