Synthesis of CdTe quantum dots using a heterogeneous process at low temperature and their optical and structural properties

Luminescent CdTe quantum dots (QDots) have been synthesized through a low-temperature process employing a heterogeneous reaction between cadmium acetate and tri-n-octyl phosphine tellurium (TOPTe) in the presence of tri-n-octyl phosphine oxide (TOPO). UV-visible absorption spectra revealed that monodispersed CdTe QDots were synthesized at 70 °C for 240 min. The as-synthesized CdTe QDots exhibited photoluminescence (PL) with a narrow spectral distribution (FWHM41 nm). Highly luminescent CdTe QDots with PL quantum yield (QY) up to 33% were size selected from the ensemble. X-ray and electron diffraction measurements revealed that CdTe crystallized in a wurtzite-type structure at 70 °C. High-resolution transmission electron microscopic measurements revealed that the CdTe particles were of regular spherical morphology with an average diameter of 2.8 nm. The present experiment demonstrates, in addition to an advantage in green chemistry, that a low-temperature process allows an extended period of time for crystallization that is useful for synthesizing defect-free QDots with higher PL QY. PACS 81.07.-b; 81.20.-n; 81.07.Ta; 78.67.-n; 61.46.+w