Aerosol-Phase Synthesis and Processing of Luminescent Silicon Nanocrystals.
Aerosol-Phase Synthesis and Processing of Luminescent Silicon Nanocrystals.
复制标题
发光硅纳米晶体的气溶胶相合成和加工。
DOI：
10.1021/acs.chemmater.9b02743
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Kortshagen,UweR
中科院分区：
文献类型：
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作者：
Li,Zhaohan;Kortshagen,UweR
硅量子点是一种极具吸引力的发光器件和生物成像材料。对于这些发光应用，为了获得更好的器件性能，需要更高的光致发光效率。低温等离子体合成成功地实现了硅纳米晶的连续生产，但后续处理是提高光致发光量子产率所必需的，从而使纳米晶可以用于发光应用。在这项工作中，我们展示了一种全气相合成和加工路线，它集成了非热等离子体合成、等离子体辅助的表面官能化和烯烃配体的表面官能化，以及在一个流程中的动态热处理。在这里，发光硅纳米晶体的合成和后处理仅需100ms的时间尺度，这比以前的合成和功能化方案快了一个数量级。所制备的硅纳米晶的光致发光量子产率超过20%，比以前用全气相合成的硅纳米晶提高了5倍。我们将这种增强的光致发光归因于动态退火热处理引起的悬挂键密度的降低和表面硅基物种的脱附，从而减少了“暗”纳米晶的比例。我们还证明了配体覆盖对光致发光性质的影响不大，但氢化硅表面基团的性质是一个主要因素。
Silicon quantum dots are attractive materials for luminescent devices and bioimaging applications. For these light-emitting applications, higher photoluminescence efficiency is desired in order to achieve better device performance. Nonthermal plasma synthesis successfully allows for the continuous production of silicon nanocrystals, but postprocessing is necessary to improve photoluminescence quantum yields so that nanocrystals can be used for luminescence applications. In this work, we demonstrate an all-aerosol-phase synthesis and processing route that integrates nonthermal plasma synthesis, plasma-assisted surface functionalization with alkene ligands, and in-flight annealing within one flow stream. Here, luminescent silicon nanocrystals are synthesized and postprocessed on a time scale of only 100 ms, which is orders of magnitude faster than previous synthesis and functionalization schemes. The as-produced silicon nanocrystals have photoluminescence quantum yields exceeding 20%, which is a 5-fold increase compared to previous silicon nanocrystals synthesized with all-aerosol-phase approaches. We attribute the enhanced photoluminescence to the reduced “dark” nanocrystal fraction due to reduction of dangling bond density and desorption of surface silyl species induced by the in-flight annealing. We also demonstrate that the ligand coverage plays a minor role for the photoluminescence properties, but that the nature of the silicon hydride surface groups is a major factor.