Chemical Engineering and the Energy Center, Purdue University, West Lafayette, Indiana 47907, USA.
J Am Chem Soc. 2011 Nov 2;133(43):17239-47. doi: 10.1021/ja204230d. Epub 2011 Oct 6.
Copper, indium, and gallium chalcogenide nanocrystals (binary, ternary, and quaternary) have been used to fabricate high-efficiency thin-film solar cells. These solution-based methods are being scaled-up and may serve as the basis for the next generation of low-cost solar cells. However, the formation pathway to reach stoichiometric ternary CuInSe(2) or any chalcopyrite phase ternary or quaternary nanocrystal in the system has not been investigated but may be of significant importance to improving nanocrystal growth and discovering new methods of synthesis. Here, we present the results of X-ray diffraction, electron microscopy, compositional analysis, IR absorption, and mass spectrometry that reveal insights into the formation pathway of CuInSe(2) nanocrystals. Starting with CuCl, InCl(3), and elemental Se all dissolved in oleylamine, the overall reaction that yields CuInSe(2) involves the chlorination of the hydrocarbon groups of the solvent. Further, we show that the amine and alkene functional groups in oleylamine are not necessary for the formation of CuInSe(2) nanocrystals by conducting successful syntheses in 1-octadecene and octadecane. Hence, the role of oleylamine is not limited to nanocrystal size and morphology control; it also acts as a reactant in the formation pathway. Typically, the formation of copper selenide (CuSe) and indium selenide (InSe) nanocrystals precedes the formation of CuInSe(2) nanocrystals in oleylamine. But it was also found that Cu(2-x)Se (0 < x < 0.5) and In(2)Se(3) were the primary intermediates involved in the formation of CISe in a purely non-coordinating solvent such as 1-octadecene, which points to the surface-stabilization effect of the coordinating solvent on the less thermodynamically stable indium selenide (InSe) nanocrystals. We also show that the yield of the chalcopyrite phase of CuInSe(2) (as opposed to the sphalerite phase) can be increased by reacting CuSe nanocrystals with InCl(3).
铜、铟和镓的硫属化物纳米晶体（二元、三元和四元）已被用于制造高效薄膜太阳能电池。这些基于溶液的方法正在规模化，并可能成为下一代低成本太阳能电池的基础。然而，尚未研究达到化学计量比的三元 CuInSe2 或该体系中任何黄铜矿相三元或四元纳米晶体的形成途径，但这可能对改善纳米晶体生长和发现新的合成方法具有重要意义。在这里，我们展示了 X 射线衍射、电子显微镜、成分分析、红外吸收和质谱的结果，这些结果揭示了 CuInSe2 纳米晶体形成途径的一些见解。从 CuCl、InCl3 和元素 Se 全部溶解在油胺中开始，生成 CuInSe2 的总反应涉及溶剂中烃基的氯化。此外，我们通过在 1-十八烯和十八烷中成功进行合成，表明油胺中的胺和烯基官能团对于 CuInSe2 纳米晶体的形成不是必需的。因此，油胺的作用不仅限于纳米晶体的尺寸和形态控制；它还在形成途径中充当反应物。通常，在油胺中，铜硒化物（CuSe）和铟硒化物（InSe）纳米晶体的形成先于 CuInSe2 纳米晶体的形成。但也发现，在完全非配位溶剂如 1-十八烯中，Cu2-xSe（0 < x < 0.5）和 In2Se3 是 CISe 形成的主要中间体，这表明配位溶剂对热力学上不太稳定的铟硒化物（InSe）纳米晶体具有表面稳定化作用。我们还表明，通过使 CuSe 纳米晶体与 InCl3 反应，可以提高黄铜矿相 CuInSe2（而不是闪锌矿相）的产率。
