Synthesis of CdTe quantum dots capped with castor oil using a hot injection solution method

Abstract Castor oil (CSTO), an extract from castor bean was used as capping material for CdTe quantum dots (QDs), synthesized from cadmium chloride and tellurium powder using a modified hot injection method. The formation of CdTe QDs in the colloidal solution was monitored by UV–Vis spectrophotometry. The average particle sizes were deduced from the absorption data, transmission electron microscopy (TEM) images and powdered-X-ray diffraction (p-XRD). The average particle size of CdTe QDs deduced from the UV–Vis absorption measurements range from 4.94 nm to 10.04 nm for CdTe QDs synthesized at 230 °C, 250 °C and 280 °C. TEM images of the CdTe QDs synthesized at 250 °C and 280 °C, for 2 h showed close to spherical geometry with average diameter of 7.38 ± 0.43 nm and 9.88 ± 0.67 nm, respectively. The p-XRD patterns confirmed the presence of CdTe crystallites with a cubic phase. The average diameter of CdTe QDs as deduced from the p-XRD patterns was 7.54 ± 0.03 nm and 9.69 ± 0.13 nm, respectively, which is in good agreement with the results from TEM and UV–Vis absorption measurements. The photoluminescence spectroscopy showed the formation of nearly monodispersed particles with emission maxima at 673 nm, 714 nm and 743 nm for CdTe QDs prepared at 230 °C for 30 min, 60 min and 120 min, respectively. These results show that green biomasses are valuable eco-friendly materials which can be used to stabilize nanomaterials.