The crystalline fraction is a critical parameter for assessing the quality of silicon quantum dots (SiQDs), and its enhancement is anticipated to improve the optoelectronic performance of these materials. However, the crystalline fraction of small SiQDs produced through the pyrolysis of hydrogen silsesquioxane (HSQ) polymers still has significant potential for improvement. In this study, we successfully synthesized SiQDs with a diameter of approximately 3 nm and near-perfect crystallinity by optimizing the triethoxysilane (TES)/aqueous hydrochloric acid (HCl) volume ratio during the hydrolysis-condensation process of HSQ polymers. The SiQDs exhibited a photoluminescence (PL) center at 760 nm and an average PL quantum yield (PLQY) of 24.4%. Our findings demonstrate that the TES/aqueous HCl ratio significantly influences the proportion of cage structure and the cross-linking density of the network structure in HSQ polymers, which in turn governs SiQD size and crystallinity. A high proportion of cage structures in HSQ polymers promotes high crystallinity. Notably, an increased cross-linking density within the network structure results in elevated and uniform diffusion barriers. This phenomenon not only hinders the diffusion of silicon atoms, leading to smaller sizes but also facilitates the achievement of high crystallinity due to uniform diffusion. This work presents a novel approach to achieving exceptional crystalline in small SiQDs, with implications for advanced applications in lighting, display technologies, medical imaging, and photovoltaics.

中文翻译：

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三乙氧基硅烷衍生的硅量子点：实现小尺寸和高结晶度的新途径


晶体分数是评估硅量子点 （SiQD） 质量的关键参数，其增强有望提高这些材料的光电性能。然而，通过氢倍半氧烷 （HSQ） 聚合物热解产生的小 SiQD 的结晶部分仍具有很大的改进潜力。在本研究中，我们通过优化 HSQ 聚合物水解缩合过程中的三乙氧基硅烷 （TES）/盐酸水溶液 （HCl） 体积比，成功合成了直径约为 3 nm 且结晶度近乎完美的 SiQD。SiQD 在 760 nm 处表现出光致发光 （PL） 中心，平均 PL 量子产率 （PLQY） 为 24.4%。我们的研究结果表明，TES/HCl 水溶液比率显着影响 HSQ 聚合物中笼状结构的比例和网络结构的交联密度，这反过来又决定了 SiQD 的尺寸和结晶度。HSQ 聚合物中高比例的笼状结构促进了高结晶度。值得注意的是，网络结构内交联密度的增加导致扩散势垒升高且均匀。这种现象不仅阻碍了硅原子的扩散，导致尺寸更小，而且由于均匀扩散，还有助于实现高结晶度。这项工作提出了一种在小型 SiQD 中实现出色晶体的新方法，对照明、显示技术、医学成像和光伏领域的高级应用具有重要意义。