Hua Fengjun, Erogbogbo Folarin, Swihart Mark T, Ruckenstein Eli
Department of Chemical and Biological Engineering, University at Buffalo (SUNY), Buffalo, New York 14260-4200, USA.
Langmuir. 2006 Apr 25;22(9):4363-70. doi: 10.1021/la0529106.
A facile method of preparing stable blue-emitting silicon nanoparticles that are dispersible in common organic solvents is presented. Oxidation of yellow-emitting silicon nanoparticles with an organic monolayer grafted to their surface, using either UV irradiation in solution or heating in air, converted them to blue-emitting particles. The evolution of the PL spectrum and infrared absorption spectrum of the particles was followed during the oxidation process. The PL spectrum showed a decrease in the PL emission peak near 600 nm and the appearance and increase in intensity of a PL emission peak near 460 nm rather than a smooth blue shift of the emission spectrum from yellow to blue. The organic monolayer grafted to the particle surface was not degraded by this oxidation process, as demonstrated by FTIR and NMR spectroscopy. Similar results were achieved for particles with styrene, 1-octene, 1-dodecene, and 1-octadecene grafted to their surface, demonstrating that it is the silicon nanocrystal, and not the organic component, that is essential to this process. The organic monolayer allows the nanoparticles to form stable, clear colloidal dispersions in organic solvents and provides for the possibility of further chemical functionalization of the particles. Combined with previous work on organically grafted silicon nanoparticles with green through near-infrared emission, this enables the efficient and scalable preparation of stable colloidal dispersions of organically grafted silicon nanoparticles with emission spanning the entire visible spectrum.
本文提出了一种制备可分散于常见有机溶剂中的稳定蓝色发光硅纳米颗粒的简便方法。通过在溶液中进行紫外线照射或在空气中加热，对表面接枝有有机单层的黄色发光硅纳米颗粒进行氧化，可将其转化为蓝色发光颗粒。在氧化过程中跟踪颗粒的光致发光（PL）光谱和红外吸收光谱的演变。PL光谱显示，600nm附近的PL发射峰强度降低，460nm附近出现PL发射峰且强度增加，而不是发射光谱从黄色到蓝色的平滑蓝移。傅里叶变换红外光谱（FTIR）和核磁共振光谱（NMR）表明，接枝到颗粒表面的有机单层并未因该氧化过程而降解。对于表面接枝有苯乙烯、1-辛烯、1-十二碳烯和1-十八碳烯的颗粒，也得到了类似的结果，这表明对于该过程至关重要的是硅纳米晶体，而非有机成分。有机单层使纳米颗粒能够在有机溶剂中形成稳定、澄清的胶体分散体，并为颗粒的进一步化学功能化提供了可能性。结合先前关于具有绿色至近红外发射的有机接枝硅纳米颗粒的研究工作，这使得能够高效且可扩展地制备发射涵盖整个可见光谱的有机接枝硅纳米颗粒的稳定胶体分散体。
