SYNTHESIS OF CdTe QUANTUM DOTS VIA MOLECULAR PRECURSOR METHOD AND INVESTIGATION OF THEIR OPTICAL PROPERTIES

Cadmium telluride (CdTe) quantum dots (QDs) were synthesized via a molecular precursor (hot-injection) method and their optical properties were investigated. A cadmium oleate precursor in octadecene/oleic acid was heated to 180 °C under an inert atmosphere, and a trioctylphosphine–tellurium (TOP-Te) solution was swiftly injected to initiate nucleation. By varying the growth time, the QD size was tuned, giving emission colors from green to red. The nanocrystals were characterized by UV–visible absorption and photoluminescence (PL) spectroscopy, which revealed a clear red shift in the optical spectra with increasing particle size. The QDs exhibited size-dependent optical properties consistent with quantum confinement, with the first excitonic absorption peak shifting from approximately 520 nm to 700 nm as the diameter increased. All samples showed high luminescence, with photoluminescence quantum yield (PLQY) values ranging from 60% to 90%. This colloidal synthesis at relatively low temperatures produced colloidally stable QDs with tunable band gaps. These results demonstrate a straightforward route to tailor QD optical properties by controlling the reaction time and provide insights into the growth kinetics and defect states in CdTe QDs.and provide insights into the growth kinetics and defect states in CdTe QDs.