Park Young Ho, Park Seung Min, Jung Kang-Won, Hwang Yunju, Sorcar Saurav, Moon Dae Woon, In Su-Il
Department of Energy Science and Engineering, DGIST, 333 Techno Jungang-daero, Hyeonpung-myeon, Dalseong-gun, Daegu 42988, Korea.
Department of New Biology, DGIST, 333, Techno jungang-daero, Hyeonpung-myeon, Dalseong-gun, Daegu 42988, Korea.
Materials (Basel). 2019 Apr 3;12(7):1109. doi: 10.3390/ma12071109.
In the current work, stable prenucleated PbS quantum dots (QDs) with a sub-nanometer (0.8 nm) size have been successfully synthesized via a systematically designed experiment. A detailed analysis of critical nucleation, growth, and stability for such ultrasmall prenucleated clusters is done. The experimental strategy is based on controlled concentration, temperature and injection of respective precursors, thus enabling us to control nucleation rate and separation of stable sub-nanometer PbS QDs with size 0.8 nm. Significantly, by providing additional thermal energy to sub-nanometer PbS QDs, we achieved the fully nucleated cubic crystalline structure of PbS with size of around 1.5 nm. The size and composition of the prenucleated QDs are investigated by sophisticated tools like X-ray photoelectron spectroscopy (XPS) and medium energy ion scattering (MEIS) spectroscopy which confirms the synthesis of PbS with Pb rich surface while the UV-Vis spectroscopy and X-ray diffraction (XRD) data suggests an alternative crystallization path. Non-classical nucleation theory is employed to substantiate the growth mechanism of prenucleated PbS QDs.
在当前工作中，通过系统设计的实验成功合成了尺寸为亚纳米级（0.8纳米）的稳定预成核硫化铅量子点（QDs）。对这种超小预成核团簇的临界成核、生长和稳定性进行了详细分析。实验策略基于对各前驱体浓度、温度和注入的控制，从而使我们能够控制成核速率并分离出尺寸为0.8纳米的稳定亚纳米级硫化铅量子点。值得注意的是，通过向亚纳米级硫化铅量子点提供额外的热能，我们获得了尺寸约为1.5纳米的完全成核的立方晶型硫化铅结构。通过诸如X射线光电子能谱（XPS）和中能离子散射（MEIS）光谱等精密工具研究了预成核量子点的尺寸和组成，这些工具证实了表面富含铅的硫化铅的合成，而紫外可见光谱和X射线衍射（XRD）数据则表明了另一种结晶途径。采用非经典成核理论来证实预成核硫化铅量子点的生长机制。
