半導體量子點CdSe和CdSe/ZnSe之合成分析與性質研究

[摘要] 本研究主要是利用高溫熱裂解(thermal pyrolysis)的方式，在TOPO-HAD-TOP所建構的溶劑系統中，分別以氧化鎘和硒製備半導體量子點硒化鎘，以及再由硒化鎘為前驅物與硬脂酸鋅製備半導體量子點(quantum dots)硒化鎘/硒化鋅。製程中依據反應時間的長短來控制粒徑大小，並改變不同的鎘和硒莫耳數比來合成硒化鎘量子點。另外，將硒化鎘與發光材料Tb(TMHD)3-DPSO和OC1C8-PPV摻混，研究其光學性質上的差異。在結構性質的部分，利用紫外光-可見光吸收光譜儀、螢光光譜儀，做光學上的分析及能隙、量子產率計算，以場發射掃描式電子顯微鏡、動態光散射粒徑分析儀，觀察粒徑大小及分布，並利用X光能量散佈光譜儀、X光粉末繞射儀，分析其元素組成及晶體結構。由實驗結果顯示，硒化鎘量子點為wurtzite結構，屬於六方最密堆積，粒徑約為4-9nm之間，放光波長綠~紅色。隨著反應時間越久，顆粒越大，發光波長也將隨著粒徑而紅位移。當鎘和硒莫耳數比愈小時，波長會有藍位移現象，且可得到粒徑較小的顆粒、量子產率較高。經由硒化鎘包覆一層硒化鋅形成一核殼結構，明顯提升了量子產率。最後，在硒化鎘摻混發光材料的部分，對Tb(TMHD)3-DPSO而言，可減少雜訊短波長的放光，進而讓材料放光更集中。反觀，對OC1C8-PPV而言，似乎降低了原本材料的吸收強度，不過真正的效果還是要製作成高分子發光二極體(polymer light-emitting diodes, PLED)元件之後，去做量測，才能進一步加以確認。

關鍵字

量子點；高溫熱裂解；硒化鎘/硒化鋅；發光材料；核殼結構；摻混；硒化鎘

並列摘要

[Abstract] The investigations towards CdSe based semiconductor quantum dots are conducted by using CdO and Se as precursors in the TOPO-HAD-TOP solvent system via thermal pyrolysis. Similarly, CdSe and zinc stearate were used as precursors to prepare CdSe/ZnSe based semiconductor quantum dots. Preparations of the semiconductor quantum dots were achieved by changing the molar ratios between Cd and Se. The particle size distribution of the semiconductor quantum dots was found to be reaction time dependent. CdSe were blended with luminescence materials such as Tb(TMHD)3-DPSO and OC1C8-PPV, and the resulting optical properties thus were studied. The structure properties were obtained by UV-Vis absorption and fluorescence spectroscopy. The properties include the optical analysis, quantum yield, and energy gap. Field-emission scanning electron microscope and dynamic light scattering particle size analyzer were employed to measure the particle size distributions. The elemental compositions and crystalline structures were demonstrated by X-ray energy dispersive spectrometer and X-ray powder diffractometer. The semiconductor quantum dots were found to be a wurtzite structure (hexagonal closet packing). The particle size distribution was determined to be 4~9nm with a green to red emission color. The particle of the semiconductor quantum dots gets bigger when the reaction time is elongated. A red shift of the emission wavelength was also observed. However, the particle of the semiconductor quantum dots gets smaller when the molar ratio between Cd and Se gets smaller. A blue shift of the emission wavelength and higher quantum yield are observed. CdSe with a ZnSe core-shell leads to a higher quantum yield. When CdSe was blended with Tb(TMHD)3-DPSO luminescence material, the emission at the short wavelength decreased and the strength at the emission wavelength gets more focused. The emission intensity is reduced with the blending of OC1C8-PPV luminescence material, and the effects on the corresponding PLED devices still need further studies.

並列關鍵字

quantum dots ； CdSe/ZnSe ； core/shell ； CdSe ； luminescence material ； blend ； thermal pyrolysis

參考文獻

52. 王子賢、李文乾，「生醫生化用途之奈米微粒」，化工，50卷2期(92年4月)，頁44-53。

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半導體量子點CdSe和CdSe/ZnSe之合成分析與性質研究

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