新穎鈰離子激活矽硫化物螢光體之合成、發光特性與其在白光發光二極體應用之研究

Abstract

本研究利用固態合成法成功製備Ce3+激活之La2SiS5及La6Si4S17矽硫化物和La3Cl(SiS4) 2鹵矽硫化物螢光體。我們利用X光粉末繞射儀與螢光光譜數據研究上述螢光粉之最佳合成條件及活化劑最佳摻雜濃度，並藉由紫外可見光光譜、熱消光實驗、量子效率測定與色度座標量測以進行螢光體發光及色度學特性分析。 本研究所合成之Ce3+摻雜矽硫化物螢光體，激發波段於近紫外光區至藍光，放射波長介於藍至黃綠光波段，可搭配不同波長之藍光二極體晶片以封裝為白光發光二極體。 本論文第一部份探討不同螢光體之最佳製備條件、X光粉末繞射晶相之分析鑑定，第二部分探討摻雜活性劑濃度最佳化、發光與光譜特性、色度座標、漫反射光譜及熱消光效應。第三部分則探討上述矽硫化物應用於白光發光二極體封裝之發光特性、演色性及色溫。

White LEDs are generally manufactured by a combination of blue or near-UV LED chips with R/G/B phosphor. We attempted to sinter new kind of thiosilicate phosphors as host matrices because of a relatively low sintering temperature and various luminescence wavelengths from blue to infrared. In this study, we have synthesized several new Ce3+-activated phosphors with La2SiS5, La6Si4S17 and La3Cl(SiS4)2 by using solid-state method in evacuated sealed quarz glass tubes. The excitation band of three Ce3+-doped phosphors are in the range of near-UV to blue, and the emission wavelengths are in the visible range between 470 nm to 520 nm. It is suitable for fabrication of white-light emitting diodes (WLED). We have also reported the optimization of synthetic conditions, the analysis results using XRD, electron microscopy to investigate microstructures, the characterized photoluminescence spectroscopy, quantum efficiency, diffuse reflection spectrometry and thermal luminescence quenching measurements. Finally, we evaluated the potential applications of fabricated WLEDs using the phosphors we synthesized in combination with respective LED chips.