螢光燈與發光二極體用新穎螢光體之設計製備與發光特性鑑定

Abstract

本研究成功地以高溫固態合成技術，製備各四種可應用於螢光燈與近紫外光發光二極體或藍光發光二極體之螢光粉。 其中紫外波長(254 nm)可激發之四種螢光粉： (1) S螢光粉，以254 nm波長激發可放射波長為542 nm之綠光，而將S螢光粉封裝於冷陰極螢光燈管中，所測得之色度座標為(0.33, 0.35)之綠光。 (2) T系列螢光粉中，T為最佳化組成，其呈現最強的紅光放射。在5D0→7FJ=0, 1, 2, 3, 4的放射峯群中，其5D0→7F2之紅光放射呈現最高強度。由T所封裝的紅光緊湊型螢光燈，其點燈壽命優於Y2O3:Eu3+商品所製成之紅光螢光燈。 (3) U螢光粉可藉由有效能量轉移機制，以254 nm波長激發可放射高強度綠光。此能量轉移被證實為偶極-偶極型的交互作用，其能量轉移臨界距離為7.6 Å。由U所封裝的綠光緊湊型螢光燈，其點燈壽命優於CeMgAl11O19:Tb3+商品所製成之綠光螢光燈，故具備應用之潛力。 (4) 深紅光V螢光粉，以254 nm波長激發，放射波長為637 nm寬帶紅光。將V封裝成紅光緊湊型螢光燈，其結果顯示此螢光材料適合用於高演色螢光燈。 此外，在近紫外波長或藍光波長可激發之四種螢光粉，分別為：(1) 以365 nm波長激發可放射420 nm寬帶藍光之W螢光粉； (2) 以355 nm波長激發可放射不同色調可見光之寬帶X螢光粉； (3) 以460 nm波長激發可放射650 nm寬帶紅光之Y螢光粉； (4) 以450 nm波長激發可放射605 nm寬帶黃橘光之Z螢光粉。另外，本研究亦將上述四種新穎螢光粉搭配適當發光二極體晶片封裝為白光發光二極體並進行評估，結果顯示其具備固態照明應用潛力。

We have successfully synthesized two series of phosphors for applications in fluorescent lamps and in NUV/blue LEDs via solid-state technique. First, we have studied four types of short UV-excited phosphors. (1) In S system, the green light have been reported and the dominant emission wavelengths was found to be 542 nm under excitation at 254 nm. The S can be fabricated cold cathode fluorescent lamp and was found to emit green light and have the CIE of (0.33, 0.55). (2) We have investigated the luminescence of a series of T phosphors and discovered that T exhibit the most intense red-emission. Among the different emission transitions 5D0→7FJ=0, 1, 2, 3, 4 of this phosphor, one particular transition (5D0→7F2) at 610 nm has been found. We have also made an attempt to observe a strong red emission displayed by this phosphor to serve as a coating material in compact fluorescent lamps (CFLs). The results clearly indicate that the life time of CFLs based on T was found to be much longer than that using Y2O3:Eu3+. The good performances of the CFLs demonstrate that this phosphor may be suitable for application in short ultraviolet fluorescent lamp. (3) Intensely green-emitting phosphors U exhibit efficient energy transfer under 254 nm excitation. The energy transfer from Ce3+ to Tb3+ has been demonstrated to be a resonant type via a dipole–dipole mechanism with the energy-transfer critical distance of 7.6 Å. We have also observed a strong green emission displayed by this phosphor for use as a coating material in CFLs. The results clearly indicate that the life time of CFLs based on U was found to be much longer than that using CeMgAl11O19:Tb3+. (4) An unprecedented deep red-emitting phosphor, V, shows a strong red emission centered at 637 nm under 254 nm excitation. We have also made an attempt to observe strong red emission displayed by V for use as a coating material in CFLs. It is a promising candidate for application in CFLs with high CRI as a red-emitting color converter. Subsequently, we have also studied four types of NUV- or blue-excited phosphors. (1) The W phosphor exhibits a broad blue emission band centering at 420 nm under 365 nm excitation. (2) The X phosphor has tunable color features under 355 nm excitation. (3) The Y phosphor exhibits a strong red emission centered at 650 nm under 460 nm excitation. (4) Upon the excitation at 450 nm, the Z phosphor exhibits a strong yellowish-orange emission centered at 605 nm with good thermal stability. All of these phosphors have been evaluated as candidates for solid-state lighting devices based on near-UV or blue LEDs.