碲化鎘量子點之微波水熱合成 及其在白光發光二極體封裝之應用

Abstract

量子點具備獨特之發光特性，如尺寸量化的放光、較窄的放射波段與光穩定性的關係，使其在光電領域的應用甚具潛力，本研究主要著重於水溶性碲化鎘量子點的製備、特性鑑定與其在LED發光二極體封裝應用之探討。在量子點的製備上，係使用微波輔助水熱法並以硝酸鎘作為含鎘前驅物，利用含有硫醇基的硫代蘋果酸(MSA)與乙醯半胱氨酸(NAC)作為不同的包覆劑，以合成一系列發綠光至紅外光的水溶性碲化鎘量子點，並探討其光學性質。 選擇適當發光波長的CdTe@MSA與CdTe@NAC量子點，作為黃光、綠光與紅光的來源，激發光源為365 nm的UV光晶片，分別可封裝出CRI值為87.8與84.1，CIE座標為(0.486,0.374)與(0.518,0.411)的發光元件，進一步將CdTe量子點轉移至利於封裝製程操作的甲苯，可成功封裝出CRI值為88.4，CIE座標為(0.397,0.322)，更加接近理想的白光LED發光元件。

Quantum dots (QDs) possess uniquely particle size-dependent luminescence such as size-quantized emission color, narrow emission spectral range, and photo stability, which make them exhibiting great potential in optoelectronic applications. With microwave-assisted hydrothermal reaction route, we have synthesized water-soluble and green-to-red emitting MSA- and NAC-capped CdTe QDs from Cd(NO3)2 as a Cd source and investigated their optical and luminescence properties. Selection of QDs with proper wavelengths as sources of yellow, green and red lights, white-light emitting devices (WLED) pumped with a 365 nm UV LED chip can be fabricated. The color rendering index (Ra) and CIE chromaticity coordinates were found to be 87.8 and 84.1 and (0.486,0.374) and (0.518,0.411) for WLEDs with CdTe@MSA and CdTe@NAC QDs, respectively. Furthermore, a WLED fabricated with QDs/toluene was found to give Ra and CIE chromaticity coordinates 88.4 and (0.397,0.322), respectively, which is closer to those of an ideal WLED.