Yu Kui, Singh Shanti, Patrito Natasha, Chu Virginia
Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada.
Langmuir. 2004 Dec 7;20(25):11161-8. doi: 10.1021/la049202p.
Using cadium oxide (CdO) as the Cd precursor and tri-n-octylphosphine selenide (TOPSe) as the Se source, TOP-capped and TOP/tri-n-octylphosphine oxide (TOPO)-capped CdSe nanocrystals were synthesized without the use of an acid. The synthetic approach involved the addition of a TOPSe/TOP solution into a CdO/TOP solution with or without TOPO at one temperature and subsequent growth at a lower temperature. The temporal evolution of the optical properties, namely, absorption and luminescence, of the growing nanocrystals was monitored in detail. A comprehensive examination on the control of the photoluminescence (PL) properties was performed by systematically varying the TOP/TOPO weight ratio of the reaction media. Surprisingly, a rational choice of 100% TOP or 80% TOP was found to produce "quality" nanocrystals when monitored under the present experimental conditions and growth-time scale. The term "quality" is mainly based on the sharp features and rich substructure exhibited in the absorption spectra of the growing nanocrystals, as well as the sharp features in the emission spectra with narrow full width at half-maximum (fwhm). There are two distinguishable stages of growth: an early stage (<5 min) and a later stage. TOP plays a major role in the control of a slow growth rate in the early stage, while TOPO controls slow growth in the later stage. The optical sensitivity of the growing nanocrystals when dispersed in nonpolar or polar solvents was studied, including two size-dependent parameters, namely, the solvent sensitivity (PL intensity) and nonresonant Stokes shift (NRSS). The insights gained from the present study enable a synthetic approach in which high-quality CdSe nanocrystals are achieved with high synthetic reproducibility.
以氧化镉（CdO）作为镉前驱体，三正辛基膦硒化物（TOPSe）作为硒源，在不使用酸的情况下合成了TOP包覆以及TOP/三正辛基氧化膦（TOPO）包覆的CdSe纳米晶体。合成方法包括在一个温度下将TOPSe/TOP溶液添加到含有或不含有TOPO的CdO/TOP溶液中，随后在较低温度下生长。详细监测了生长中的纳米晶体光学性质（即吸收和发光）随时间的演变。通过系统改变反应介质的TOP/TOPO重量比，对光致发光（PL）性质的控制进行了全面研究。令人惊讶的是，在当前实验条件和生长时间尺度下监测发现，合理选择100% TOP或80% TOP可产生“高质量”的纳米晶体。“高质量”这一术语主要基于生长中的纳米晶体吸收光谱中呈现的尖锐特征和丰富子结构，以及发射光谱中半高宽（fwhm）较窄的尖锐特征。生长过程有两个可区分的阶段：早期阶段（<5分钟）和后期阶段。TOP在控制早期缓慢生长速率方面起主要作用，而TOPO控制后期的缓慢生长。研究了生长中的纳米晶体分散在非极性或极性溶剂中的光学灵敏度，包括两个尺寸依赖性参数，即溶剂灵敏度（PL强度）和非共振斯托克斯位移（NRSS）。本研究获得的见解使得能够采用一种合成方法，以高合成重现性实现高质量的CdSe纳米晶体。
