Synthesis of a rare Earth Free Oxynitride Phosphor for white LED Application

Abstract

The purpose of this research was to promote the performance of rare earth free oxynitride phosphor (BCNO: boron carbon oxynitride) for next generation of white LED. In particular, I undertook the following research topics, (1) Preparation of spherical BCNO phosphor particle via spray pyrolysis and (2) Enhancement of Photoluminescence intensity of BCNO phosphor using nitrogen containing polymer.

Regarding (1), spherical BCNO phosphor particles were directly synthesized by a modified spray pyrolysis method using water trap. Effect of operating temperature and polymer concentration on the photoluminescence properties were investigated. Scanning electron microscopy revealed that the spherical particles were of size around 1.36 mm. The emission band of the spherical BCNO phosphor prepared at 800℃ was observed at 467 nm under excitation at 365 nm.

Regarding (2), three types of polymers, including polyethyleneimine (PEI), polyallylamine (PAA), and tetraethylene glycol (TEG) were used as carbon sources for the formation of BCNO phosphors. PEI was found to have the highest internal quantum efficiency (IQE) of the three polymers because of its optimum thermal decomposition temperature and high exothermic energy during BCNO formation. The IQE of the BCNO phosphors prepared with PEI was 50%, representing a 130% increase over the value observed when TEG was used as the carbon source. In addition, the emission band of the BCNO phosphors could be tuned from 380 to 490 nm by varying the reaction temperature and polymer concentrations.