白光LED轉換螢光材料之製備與發光特性鑑定

Abstract

本研究成功地以高溫固態法配合弱還原條件，合成四種含不同活化離子共摻單一主體之白光螢光材料，作為新開發紫外光發光二極體晶粒轉換為白光，並取代傳統的藍光發光二極體晶粒。 在(Y0.65Gd0.35)BO3與Y2SiO5兩主體中，本研究藉由摻雜不同比例的三種稀土活化劑( Ce3+,Tb3+,Eu3+ )，以供此兩螢光體分別在361nm及358nm之長波長紫外光源激發下，發射出接近理想白光。而主體(Sr0.5)Ba0.5Al2S4則是於密閉石英管中所合成，再藉由Eu2+摻雜離子後，調變其藍光峰帶與紅光峰帶產生重疊與消長之現象。當光源激發波長為395nm時，(Sr0.5)Ba0.5Al2S4: Eu2+螢光體達到色度均衡而發出白色光。 此外，(Sr0.9Mg0.1)3(PO4)2則是一種菱形結構之化合物，本研究深入探討摻雜離子濃度對其發光特性及輝度所造成的影響。本研究發現4 mole% Sn2+及1 mole% Cu+共摻時，在紫外光激發之下，能使其螢光放射強度( 1:2 )及輝度( 2:1 )比例達到均衡，對色度產生對等地貢獻，因而形成白光。

To investigate the potential phosphors for applications in white light ultraviolet light emitting diodes(UV-LED), we have synthesized four types of phosphors with different activator doping via solid-state route. This research is attempted to investigate the correlation of activator doping and the chromaticity of white light generated from combination of UV-LED and proper phosphors. In the phosphors with hosts of (Y0.65Gd0.35)BO3 and Y2SiO5 we have investigate the codoping effect with activators of Ce3+, Tb3+ and Eu3+, respectively. These two types of phosphors emit white light under the excitation of ultraviolet radiation with wavelength of 361 nm and 358 nm, respectively. On the other hand, by tuning the overlapping of blue and red emission, the Eu2+-doped (Sr0.5Ba0.5)Al2S4 synthesized in a sealed quartz tube also emits white light under the excitation of ultraviolet of 395 nm. In addition, we have also investigated the luminescence and chromaticity characteristics of rhombohedral (Sr0.9Mg0.1)3(PO4)2:Sn2+,Cu+ phosphors as a function of activator concentrations. Under ultraviolet excitation this phosphate phosphor was found to generate well-balanced white light with decent luminescence and brightness.