Band-Emission Evolutions from Magic-sized Clusters to Nanosized Quantum Dots of Cd3As2 in the Hot-Bubbling Synthesis

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• 作者：Mei Huang ; Stephen G. Hickey ; Bianc H枚fer ; Fei Ding ; Shuai He ; Oliver G. Schmidt ; Alexander Eychm眉ller ; Shiding Miao
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：July 16, 2015
• 年：2015
• 卷：119
• 期：28
• 页码：16390-16395
• 全文大小：364K
• ISSN：1932-7455

文摘

In this work, the band-emissions of both the magic-sized clusters (MSCs) and nanosized quantum dots (QDs) of cadmium arsenide (Cd₃As₂) are studied versus time during the hot-bubbling synthesis. The syntheses are performed by introducing the ex-situ produced H₃As into the hot-surfactant solutions dissolved with cadmium oleate and ligand molecules. It is found that the MSCs are produced within 4.0 min because of the color change of the solution. However, these clusters are not stable, and the peak of the photoabsorption shifts from 528 to 540 nm with the growth time. Across a shallow energy barrier, the MSCs grow into nanosized quantum dots whose photoluminescence wavelengths are found to extend into the NIR region (位 > 1480 nm) after a growth period of 鈭?5.0 min. The quantum yield of the band emissions ranges 2.5鈥?.0% during the growth of Cd₃As₂ QDs. Analyses from the time-resolved fluorescence decay profiles suggest that the ultrafast exciton radiative decays are the dominant recombination in the Cd₃As₂ MSCs, and the lifetime is about 0.69 ns. Longer lifetime emissions (200鈥?00 ns) are found in the nanosized QDs, which is ascribed to the delocalized excitons in the lowest QD state after thermalization. This research highlights the origin and evolution of band-emissions in Cd₃As₂ QDs, which gives an in-depth understanding of the electronic structures of Cd₃As₂ QDs, and thus lending them wider potential applicability.