- 學位論文
提升螢光金奈米團簇光激螢光之研究
Studies of Photoluminescence Enhancement in Fluorescent Gold Nanoclusters
摘要
本文利用光激螢光光譜以及時間解析光激螢光光譜來研究螢光金奈米團簇接上不同配體後的增強螢光強度的發光機制。於時間解析光激螢光光譜中擬合出變溫下輻射復合生命期，發現符合量子點之輻射衰減率理論，因此推論螢光金奈米團簇披覆聚二乙醇為零維載子的 現象。 在接枝上聚二乙醇後，明顯發現螢光強度的增加，利用變溫下螢光強度以及低溫下侷限深度，得知接枝後的侷限深度約增加1倍。此外，根據螢光強度、載子生命期及輻射復合生命期的關係式，擬合出螢光強度的變化為1.56倍。 螢光金奈米團簇披覆二氧化矽在快速熱退火處理後，材料的品質有所提升，當熱退火溫度在60 ℃時，室溫下光激螢光強度比未處理樣品的螢光強度增加45倍。利用比率方程式來擬合其活化能，得知熱退火後的活化能相對減小。故推測在快速熱退火後，螢光金奈米團簇的載子多了一種轉移路徑，致使更多高能階的載子轉移於低能階。
並列摘要
In this thesis, we study the enhanced quantum yield of luminescence in fluorescent Au nanoclusters (NCs) with different ligands by photoluminescence (PL) and time-resolved photoluminescence (TRPL). The zere-dimensionality of carriers in Au NCs coated with polyethylene glycol (PEG) (Au NCs@PEG) was demonstrated by temperature dependence of the TRPL. We explore the pronounced increase of luminescence intensity after coating with PEG. The energy of localization is about 1-fold increase at low temperature. Based on studies of fluorescence intensity, carrier lifetime and the radiative lifetime, the intensity of luminescence is increased for 1.56 times. The fluorescent Au nanoclusters after silica coating can improve the quality by the rapid thermal annealing (RTA). The room-temperature luminescence of Au clusters after RTA at 60 ℃is 45-fold increased than that of the untreated sample. In the temperature-dependence studies of PL, we used the rate equation to fit the activation energy that is decreases after RTA. We suggest that the carriers of fluorescent Au NCs have more paths after RTA, leading to the transfer from the high-energy state to the low-energy state.