A tm3+/dy3+ doped liyf4 single crystal for white light led and its preparation method

Abstract

The invention discloses a Tm<3+> / Dy<3+> doped LiYF4 monocrystal for white light LED (Light Emitting Diode) and a preparation method thereof. The LiYF4 crystal contains two rare earth ions, namely, Tm<3+> and Dy<3+>, the molecular formula of a product is LiY(1-alpha-beta)Tm alpha Dy beta F4, wherein alpha is not smaller than 0.0020 but not larger than 0.0300, and beta is not smaller than 0.0076 and not larger than 0.01140. Blue green light and yellow light emitted by Dy<3+> are mixed with blue light emitted by Tm<3+> to emit white light. When the atom concentration proportion of Tm<3+> / Dy<3+> in the crystal reaches to 3.7-3.9, the chromaticity coordinates of white light are optimal under the excitation of 350nm light, and the chromaticity coordinates x and y are basically close to the ideal 0.33. The doping concentration of rare earth in the lithium yttrium fluoride monocrystal is large, and the lithium yttrium fluoride monocrystal has excellent thermal, mechanical and chemical stability. The light emitting efficiency of the Eu<3+> and Dy<3+> rare earth ions doped in the monocrystal is high; and oxygen-free and water-free sealed Bridgman-Stockbarger method is adopted in the preparation method, and a high temperature fluorination treatment is performed on the raw material to obtain a fluoride crystal with high quality.

Description

technical field [0001] The invention relates to white light LEDs, in particular to a Tm for white light LEDs 3+ / Dy 3+ Doped LiYF 4 Single crystal and its preparation method. Background technique [0002] LED (Light-emitting diode) is a new semiconductor solid-state light source that converts electrical energy into light energy. Due to its energy-saving, environmental protection, long life, low-voltage safety, miniaturization, and low loss, it has become the fourth-generation new lighting source. Realize real energy saving and green lighting. At present, most LED lighting devices are made of blue-emitting LED chips (mainly InGaN) and yellow phosphors (Ce 3+ :YAG) packaged together, the blue light emitted by the chip and the yellow light generated by the phosphor excited by the blue light are mixed into white light emission, but there are the following defects: (1) the color temperature of white light is high, and the color rendering index is low; (2) White light is eas...

AI Technical Summary

Problems solved by technology

At present, most LED lighting devices are made of blue-emitting LED chips (mainly InGaN) and yellow phosphors (Ce 3+ :YAG) packaged together, the blue light emitted by the chip and the yellow light generated by the phosphor excited by the blue light are mixed into white light emission, but there are the following defects: (1) the color temperature of white light is high, and the color rendering index is low; (2) White light is easy to distort and drift, resulting in slightly blue or yellowish white light; (3) the coated phosphor has an adverse effect on white light due to the uneven particle size; (4) the organic epoxy resin used for encapsulation is in the light It is easy to age under irradiation; (5) the cost is higher, etc.

(3) High luminous intensity of rare earth ions, etc.; however, luminescent glass has major shortcomings such as physicochemical, thermal, anti-light radiation, and poor luminescent performance of rare earth ions, which have become the biggest bottleneck restricting its large-scale practical application