InP/ZnS核殼量子點應用-無重金屬發光二極體與藉由銀奈米立方體的螢光增強

Abstract

奈米尺寸半導體量子點的能階隨粒徑大小與組成元素而改變，具有獨特之光學特性。其應用量子點發光二極體(QDs-LEDs)具有高色彩純度、透明度、可延展性且具經濟效益的顯色技術。然而過去量子點主要以鎘(Cd)為主材料，其因為毒性限制了發展。近年來主要的研究為尋找鎘的替代材料，而磷化銦(InP)為主體的量子點因在光電特性上的表現而逐漸嶄露頭角。 本篇論文中，我們為了開發友善環境且低毒性無重金屬的量子點LED，我們使用高溫注射法合成無重金屬之InP/ZnS核殼量子點，並以低成本且安全的前驅物(DMA)3P取代以往危險且昂貴的前驅物，接著在其外層包覆硫化鋅(ZnS)，最後形成磷化銦/硫化鋅核殼量子點。再將測試磷化銦/硫化鋅核殼量子點光學特性、結構、熱穩定性後，將其製成量子點LED，最後測試其光電性能。 再者，我們研究藉由銀奈米立方體(Ag nanocube)，增強InP/ZnS量子點之螢光。依序利用銀奈米立方體和製備之磷化銦/硫化鋅核殼量子點在玻璃基板上成薄膜，測試其金屬增強螢光(Metal Enhanced Fluorescence, MEF)之效果。初步測試發現確實有螢光增強之效果。

Semiconductor quantum dots (QDs), of which particle sizes are in the nanometer scale, have unique size-controllable optical properties. Quantum dots light emitting diodes (QDs-LEDs), which is application of QDs, have been considered as potential display technologies with the characterizations of high color purity, flexibility, transparency and cost efficiency. For the practical applications, the development of heavy-metal free QDs-LEDs from environment-friendly materials is the most important issue to reduce the impacts of human health and environmental pollution. In this work, heavy-metal free InP/ZnS core/shell QDs were synthesized by solvothermal method with low-cost, safe and environment-friendly precursors (DMA)3P. The structural and optical characterizations demonstrated the successful syntheses of InP/ZnS core/shell QDs. The maximum fluorescence peak of InP/ZnS core/shell QDs was obtained at ~530 nm. The optimal process conditions were investigated for InP/ZnS core/shell QDs-LEDs fabrication to obtain the best performance. Overall, the multilayered InP/ZnS core/shell QDs-LEDs reveal potential to be the heavy-metal free QDs-LEDs for future display applications. On the other side, the enhancement of the fluorescence of InP/ZnS quantum dots by silver nanocubes was investigated. We sequentially deposited silver nanocubes and InP/ZnS quantum dots on ITO substrate. After preliminary testing, we found that the fluorescence of InP/ZnS quantum dot is indeed enhanced by silver nanocubes because of Metal-Enhanced Fluorescence theory.