In situ synthesis of CdTe:CdS quantum dot nanocomposites for photovoltaic applications

In this work, the selective synthesis of pure cadmium telluride (CdTe) quantum dots and cadmium telluride and cadmium sulfide (CdTe:CdS) nanocomposites was accomplished. The thiol capping agent played a dual role in the preparation of CdTe and CdTe:CdS nanocomposites. Thioglycolic acid acted as a capping agent at the starting stage of the refluxing process and also acted as a sulfur source in the fabrication of CdTe:CdS nanocomposite through partial hydrolysis at longer refluxing time. The fluorescence quantum yield of the CdTe quantum dots was significantly increased in the preparation of CdTe:CdS nanocomposites. The maximum quantum yield by CdTe:CdS nanocomposites was achieved as 47% for a refluxing time of 58 h. The structural studies revealed the formation of CdTe:CdS nanocomposites at longer refluxing time. The homogeneous size distribution of the CdTe:CdS nanocomposites was confirmed by high resolution transmission electron microscopic studies. The optical studies clearly demonstrated the formation of CdTe:CdS nanocomposites through partial hydrolysis of capping agent with the extended refluxing time. The size dependent energy transfer of the CdTe quantum dots was studied by the absorption and emission characteristics.