期刊
ACS APPLIED NANO MATERIALS
卷 6, 期 7, 页码 6444-6453出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsanm.3c01130
关键词
high-pressure water vapor annealing (HWA); silicon quantum dots; silicon oxide; quantum yield; photoluminescence
Silicon quantum dots (Si QDs) are non-toxic, elementally abundant, and low-cost luminescent materials that find applications in various fields. This study presents a convenient and rapid technique, high-pressure water vapor annealing (HWA), for synthesizing Si/SiO2 core/shell quantum dots with tunable photoluminescence. The injection of additional hydrogen gas is found to be detrimental to achieving stable silica shells, while varying the applied pressure allows for tuning of the photoluminescence quantum yield. Thicker silica shells ensure environmentally stable quantum yields of >40%.
As non-toxic, elementally abundant, and low-cost lumino-phores, silicon quantum dots (Si QDs) suit a wide variety of applications, from luminescent devices, such as solar concentrators and light-emitting diodes, to bioimaging. Nonthermal plasma-assisted decomposition of silane gas is an efficient, relatively sustainable, and controllable method for synthesizing Si QDs. However, as-synthesized Si QDs have a high defect density and require additional passivation for utilization in these settings. Liquid-based passivation methods, such as thermal hydrosilylation, organically cap Si QDs but cannot prevent oxidation upon exposure to ambient air. Native oxidation effectively passivates the Si QDs and ensures long-term stability in air but typically requires long exposures to ambient conditions. Here, we report the use of high-pressure water vapor annealing (HWA) to quickly obtain Si/SiO2 core/shell quantum dots with tunable photoluminescence (PL). We first show that the injection of additional hydrogen gas, commonly used in synthesizing organically capped Si QDs, is detrimental to achieving stable silica shells. Then, we demonstrate that varying the applied pressure tunes the PL quantum yield. At higher pressures, the formed silica shells are fully thermally relaxed. Lastly, we report the influence of silica shell thickness, with thicker silica shells leading to environmentally stable quantum yields of >40%. Compared to both thermal hydrosilylation and native oxidation, HWA is a convenient and rapid technique for surface passivation.
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