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, achieving a high crystalline fraction in small-sized SiQDs produced through the pyrolysis of hydrogen silsesquioxane (HSQ) polymers remains a significant challenge. In this study, we successfully synthesized SiQDs with a diameter of 3.24 nm and a crystalline fraction of 98.4% by optimizing the triethoxysilane (TES)/aqueous hydrochloric acid (HCl) volume ratio during the hydrolysis-condensation process. The SiQDs exhibited a photoluminescence (PL) center at 764.1 nm and an average PL quantum yield (PLQY) of 24.4%. Our findings demonstrate that the TES/aqueous HCl volume 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 crystalline fraction. A high proportion of cage structures in HSQ polymers contributes to high crystallinity. Notably, an increased cross-linking density within the network structure results in higher and more uniform diffusion barriers. This phenomenon not only hinders the diffusion of silicon atoms, which leads to smaller SiQD size, but also facilitates the achievement of high crystalline fraction due to uniform diffusion. This work presents a novel approach to achieving high crystallinity in small SiQDs, with implications for advanced applications in lighting, display technologies, medical imaging, and photovoltaics.

中文翻译：

---

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，通过倍半氧烷氢 （HSQ） 聚合物热解生产的小型 SiQD 实现高结晶分数仍然是一项重大挑战。在本研究中，我们通过优化水解-缩合过程中的三乙氧基硅烷 （TES）/盐酸水溶液 （HCl） 体积比，成功合成了直径为 3.24 nm、结晶率为 98.4% 的 SiQD。SiQD 在 764.1 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 水溶液体积比显着影响 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 的尺寸和结晶分数。HSQ 聚合物中高比例的笼状结构有助于实现高结晶度。值得注意的是，网络结构内交联密度的增加导致更高、更均匀的扩散势垒。这种现象不仅阻碍了硅原子的扩散，导致 SiQD 尺寸更小，而且由于均匀扩散，还有助于实现高结晶分数。这项工作提出了一种在小型 SiQD 中实现高结晶度的新方法，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。