無機硫化物螢光粉之製備 發光特性鑑定與包膜之研究

Abstract

SrGa2S4: Eu2+與SrS: Eu2+硫化物螢光體分別發射綠光與紅光，可搭配藍光發光二極體(LED)晶片封裝白光LED。硫化物螢光體一般較不安定，易受到氧氣、水氣或甚至紫外線的影響，而產生發光效率降低、老化與劣解現象，故其使用壽命通常較短，此為實際應用必須克服的問題。 本論文成功地以固態合成法合成SrGa2S4: Eu2+與SrS: Eu2+硫化物螢光體，並以溶膠-凝膠法將二氧化矽(SiO2)、聚甲基丙烯酸甲酯(PMMA)、聚乙烯吡咯烷酮(PVP)等物質分別包覆於螢光體表面，之後再經由X光粉末繞射、螢光光譜、量子效率、CIE色度座標、傅立葉轉換紅外(FTIR)光譜、場發射穿透式與掃描式電子顯微鏡(TEM& SEM)分析，針對上述螢光體進行結構、發光特性及色度學分析鑑定，其主旨在於探討硫化物螢光粉包膜後是否有助於穩定性之提升。研究結果顯示：SrGa2S4: Eu2+與SrS: Eu2+硫化物均可被SiO2、PMMA與PVP成功包覆，且螢光體包膜後其發光強度大多數呈現下降，且在相同浸置時間，包膜硫化物較未包膜者導電度呈現下降之趨勢。

Abstract In combination with blue light emitting diode(LED), green-emitting SrGa2S4: Eu2+ and red-emitting SrS: Eu2+can be used to fabricate white-light. Sulfide phosphors suffer from material instability such as oxygen, moisture and even ultraviolet radiation damage and generate low efficiency, aging and degradation, which is considered as serious drawback in application. This research investigates encapsulation of SrGa2S4: Eu2+ and SrS: Eu2+ with SiO2, poly(methyl methacrylate) (PMMA) and polyvinylpyrrolidone (PVP) by using sol-gel method. The encapsulated phosphors were then characterized using X-Ray diffraction (XRD), luminescence and FTIR spectroscopy, FETEM and SEM microscopy, and integrating sphere to determine quantum efficiency, CIE chromaticity, and microstructures. Investigation results indicate that both SrGa2S4: Eu2+and SrS: Eu2+can be successfully encapsulated with SiO2,PMMAand PVP with thickness ranging from 26-71 nm, 170-770 nm and 250-720 nm, respectively, upon encapsulation. Our results indicate that the luminescence intensity of encapsulated sulfides decreases upon encapsulation. The electrical conductivity of encapsulated sulfides was found to decrease as compared to those without encapsulation with the same dipping time.