Low-Temperature Synthesis and Characterisation of Ultra-Small Cadmium Selenide Quantum Dots in Octadecene Solution

Semiconductor quantum dots (QDs) exhibit diverse opto-electronic properties for multi-task applications which can be stimulated by spatial control distribution of their chemical composition. These unique properties facilitated the synthesis of ultra-small non-injection one-pot cadmium selenide (CdSe) QDs in octadecene (OTD) solution at low temperature in quest for innovation-driven cost reductions of photovoltaic material. The synthesis that lasted for 2 hrs started by heating 10 ml of OTD to 35°C followed by the addition of 13 g of cadmium oxide (CdO), 0.4 ml trioctlyphosphine (TOPO), 0.6 ml of oleic acid (OA) and 5 mg of selenium (Se) powder. The heating was extended to 95°C on adding the mixtures. The optical properties of the colloidal CdSe QDs generated upon reaction were characterised using absorption spectroscopy (UV-Vis) and photoluminescence spectroscopy (PL). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed the surface morphology of the CdSe QD particles. The particle orientation and microstructure cubic structure of the lattice studied using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) revealed the cubic structure of the sample. Although the operation was safe, the low-cost reproducible low temperature synthesised high-quality CdSe QDs was stable for about five months.