Analysis of luminescence mechanism of highly efficient yag and tag phosphors for LED’s application

Abstract

The idea of a white light emitting diode (LED) seems not to be inherently unusual or surprising. It was not until the recent successful creation of high frequency light LEDs in the blue/ultraviolet region when the white LED made its debut. With the perspective of a highly efficient, cold light source, the LED market will have an enormous growth and the white LED will be a likely candidate for the replacement of the light bulb once production costs fall as the technology advances. The first commercially available white LED based on phosphors was produced by Nichia Co., which was also first to manage to make the blue LED. Nichia used a blue light emitting Gallium Indium Nitride and coated the chip with yellow fluorescent phosphor Y3Al5O12:Ce, well known now as (YAG:Ce). A little later an other yellow phosphor Tb3Al5O12:Ce (TAG:Ce) was also used with GaInN chip for white light production. Usually these TAG:Ce and YAG:Ce phosphors are synthesized by solid state reaction (SSR) method and have the similar properties. The aim of this study is to investigate the phosphors properties and luminescence mechanism of highly efficient YAG and TAG samples and propose how to improve and optimize the luminescence parameters.