Murria Priya, Miskin Caleb K, Boyne Robert, Cain Laurance T, Yerabolu Ravikiran, Zhang Ruihong, Wegener Evan C, Miller Jeffrey T, Kenttämaa Hilkka I, Agrawal Rakesh
Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States.
Davidson School of Chemical Engineering, Purdue University , 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States.
Inorg Chem. 2017 Dec 4;56(23):14396-14407. doi: 10.1021/acs.inorgchem.7b01359. Epub 2017 Nov 13.
Thiol-amine mixtures are an attractive medium for the solution processing of semiconducting thin films because of their remarkable ability to dissolve a variety of metals, metal chalcogenides, metal salts, and chalcogens. However, very little is known about their dissolution chemistry. Electrospray ionization high-resolution tandem mass spectrometry and X-ray absorption spectroscopy were employed to identify the species formed upon dissolution of CuCl and CuCl in 1-propanethiol and n-butylamine. Copper was found to be present exclusively in the 1+ oxidation state for both solutions. The copper complexes detected include copper chlorides, copper thiolates, and copper thiolate chlorides. No complexes of copper with amines were observed. Additionally, alkylammonium ions and alkylammonium chloride adducts were observed. These findings suggest that the dissolution is initiated by proton transfer from the thiol to the amine, followed by coordination of the thiolate anions with copper cations. Interestingly, the mass and X-ray absorption spectra of the solutions of CuCl and CuCl in thiol-amine were essentially identical. However, dialkyl disulfides were identified by Raman spectroscopy as an oxidation product only for the copper(II) solution, wherein copper(II) had been reduced to copper(I). Analysis of several thiol-amine pairs suggested that the dissolution mechanism is quite general. Finally, analysis of thin films prepared from these solutions revealed persistent chlorine impurities, in agreement with previous studies. These impurities are explained by the mass spectrometric finding that chloride ligands are not completely displaced by thiolates upon dissolution. These results suggest that precursors other than chlorides will likely be preferred for the generation of high-efficiency copper chalcogenide films, despite the reasonable efficiencies that have been obtained for films generated from chloride precursors in the past.
硫醇 - 胺混合物是用于半导体薄膜溶液处理的一种有吸引力的介质，因为它们具有溶解多种金属、金属硫属化物、金属盐和硫属元素的显著能力。然而，人们对它们的溶解化学了解甚少。采用电喷雾电离高分辨率串联质谱和X射线吸收光谱法来鉴定CuCl和CuCl在1 - 丙硫醇和正丁胺中溶解后形成的物种。发现两种溶液中的铜均仅以 +1氧化态存在。检测到的铜配合物包括氯化铜、硫醇铜和硫醇铜氯化物。未观察到铜与胺的配合物。此外，还观察到烷基铵离子和烷基氯化铵加合物。这些发现表明溶解过程是由硫醇向胺的质子转移引发的，随后硫醇根阴离子与铜阳离子配位。有趣的是，CuCl和CuCl在硫醇 - 胺溶液中的质谱和X射线吸收光谱基本相同。然而，通过拉曼光谱鉴定出二烷基二硫化物仅为铜（II）溶液的氧化产物，其中铜（II）已被还原为铜（I）。对几种硫醇 - 胺对的分析表明溶解机制相当普遍。最后，对由这些溶液制备的薄膜的分析揭示了持续存在的氯杂质，这与先前的研究一致。这些杂质可以通过质谱分析结果来解释，即溶解时氯化物配体不会被硫醇盐完全取代。这些结果表明，尽管过去使用氯化物前驱体生成的薄膜已获得了合理的效率，但对于生成高效铜硫属化物薄膜而言，氯化物以外的前驱体可能更受青睐。
