Generalized chemical route to develop fatty acid capped highly dispersed semiconducting metal sulphide nanocrystals

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• 作者：Jayesh D. Patel^a ; ^b ; Frej Mighri^a ; ^b ; ^{Frej.Mighri@gch.ulaval.ca} ; Abdellah Ajji^a ; ^c
• 关键词：A. Semiconductors ; B. Chemical synthesis
• 刊名：Materials Research Bulletin
• 出版年：2012
• 期刊代码：60_00255408
• 类别：ms
• 出版时间：August, 2012
• 卷：47
• 期：8
• 页码：2016-2021
• 文件大小：1002 K

摘要

This work deals with the synthesis of highly dispersed semiconducting nanocrystals (NCs) of cadmium sulphide (CdS), zinc sulphide (ZnS) and lead sulphide (PbS) through a simple and generalized process using oleic acid (OA) as surfactant. To synthesize these NCs, metal-oleate (M-O) complexes were obtained from the reaction at 140 掳C between metal acetates and OA in hexanes media. Subsequently, M-O complexes were sulphurized using thioacetamide at the same temperature. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) characterizations show that the synthesized products are of nanoscale-size with highly crystalline cubic phase. The optical absorption of OA-capped metal sulphide NCs confirms that their size quantization induced a large shift towards visible region. Photoluminescence (PL) spectrum of CdS NCs shows a broad band-edge emission with shallow and deep-trap emissions, while PL spectrum of ZnS NCs reveals a broad emission due to defects states on the surface. The thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy indicate that fatty acid monolayers were bound strongly on the nanocrystal surface as a carboxylate and the two oxygen atoms of the carboxylate were coordinated symmetrically to the surface of the NCs. The strong binding between the fatty acid and the NCs surface enhances the stability of NCs colloids. In general, this generalized route has a great potential in developing nanoscale metal sulphides for opto-electronic devices.