四價錳激活無機螢光粉之製備發光特性鑑定與應用

Abstract

Mn4+激活螢光體在藍光或紫外光的激發下，放射窄波形紅光，其激發主要源自於Mn4+ 4A2g→4T2g及4A2g→4T1g之躍遷，而光是放光源自於2Eg →4A2g之躍遷。近年來Mn4+螢光體逐漸興起，其獨特的發光特性可做為一種非稀土元素的紅光螢光體應用於暖白光LED上。 本論文成功以化學反應法合成BaGeF6 : Mn4+氟化物螢光體，此外亦以固態合成法製備La2ZnTiO6 : Mn4+ 與LaMg0.5Ti0.5O3 : Mn4+ 兩氧化物螢光體，上述Mn4+ 所取代的格位為六配位的Ge4+ 和Ti4+，並且經由X光粉末繞射、螢光光譜、量子效率、CIE色度座標、熱消光效應、漫反射光譜、掃描式電子顯微鏡及EDS分析，進行螢光體之結構、發光特性及色度學分析鑑定，進而對氟化物及氧化物Mn4+螢光粉加以比較，並進行白光LED封裝探討其應用性。由結果顯示BaGeF6 : Mn4+螢光體極具有應用於暖白光LED之潛力，其在633 nm的線性紅光可用來解決商用白光LED之色溫過高及演色性不足之問題；而La2ZnTiO6 : Mn4+以及LaMg0.5Ti0.5O3 : Mn4+螢光粉於650 nm至750 nm的放光使其具有應用於植物培養之人工照光的可能性。

Mn4+-activated phosphors exhibit narrow-line red emission under blue or UV excitation, which can be attributed to the 4A2g→4T2g and 4A2g→4T1g transitions, while the emission is attributed to the 2Eg →4A2g transition. Mn4+ red phosphors have recently been emerging as non-rare-earth red phosphors for warm white LEDs due to their unique optical property. In this thesis, we have successfully synthesized a novel Mn4+ -activated fluoride phosphor with composition of BaGeF6 : Mn4+ by chemical wet etching reaction, and Mn4+-activated oxide phosphors with composition of La2ZnTiO6 : Mn4+ and LaMg0.5Ti0.5O3 : Mn4+ by solid state reaction. Moreover, the crystal structure, luminescence and chromaticity properties of this phosphors were characterized by X-ray powder diffraction (XRD), photoluminescence spectra (PL/PLE), quantum efficiency, temperature-dependent PL spectra, diffuse reflectance spectra, SEM and EDS analysis. We also fabricated white LED devices using these phosphors. The results show that BaGeF6:Mn4+ can be a promising red phosphor for warm white LED, while the La2ZnTiO6 : Mn4+ and LaMg0.5Ti0.5O3 : Mn4+ may have the potential application in artificial lighting for plant cultivation.