Rare-earth-free fluorescent powder for white light LED and preparation method of rare-earth-free fluorescent powder

Abstract

The invention discloses rare-earth-free fluorescent powder for a white light LED and a preparation method of the rare-earth-free fluorescent powder. The rare-earth-free fluorescent powder is prepared from, by mass, 98-99.98% of metal-organic frame material, 0.01-1% of yellow light or green light emission dyestuff and 0.01-1% of red light emission dyestuff. The preparation method includes the following steps that an aromatic carboxylic acid organic ligand and metal salt are subjected to solvothermal / hydrothermal reaction synthesis to obtain the metal-organic frame material; the metal-organic frame material is soaked in a dyestuff solution, and dyestuff molecules / ions enter the metal-organic frame material. The process is simple, conditions are mild, the yield is high, the prepared fluorescent powder is free of a rare earth element, internal quantum efficiency is higher than 75%, and thermo-chemical stability is high. The rare-earth-free fluorescent powder is combined with a blue light LED chip, the color rending index of the prepared white light LED is higher than 80, the color temperature can be continuously adjusted between 2,500 K and 7,000 K, brightness is high, and under injection at the current density of 20 A / cm<2>, the lighting efficiency is higher than 140 lm / W, and luminous decay is low.

Description

technical field [0001] The invention relates to a rare-earth-free fluorescent powder and a preparation method thereof, in particular to a rare-earth-free fluorescent powder for white LEDs and a preparation method thereof. Background technique [0002] Due to its high luminous efficiency, long life, small devices, and fast response, white LEDs have developed rapidly in the past decade and are considered to be solid-state light sources that can replace incandescent and fluorescent lamps. There are many ways to realize white LED. Currently, the most mainstream way is that blue LED chip excites yellow phosphor to form white light. This solution has the advantages of simple design and high lumen efficiency. The current yellow phosphor mainly uses cerium-doped yttrium aluminum garnet (YAG:Ce) phosphor, which emits a broad-spectrum emission of about 540nm under the excitation of 450-460nm blue light, and is combined with the blue light emitted by the chip. get white light. Howeve...

AI Technical Summary

Problems solved by technology

However, due to the lack of emission of the red part of the YAG:Ce phosphor, the white LED produced by it has the disadvantages of high color temperature and low color rendering index.

At present, in order to obtain white LEDs with high color rendering index, a common solution is to add a certain amount of red powder to the yellow powder, but the reabsorption between different phosphors makes the luminous efficiency drop significantly, and due to the aging of different phosphors The characteristics and temperature characteristics are inconsistent, and the color characteristics of white LEDs will change during use

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