Co-precipitation Synthesis of CdTe/ ZnS, ZnSe, CdS and CdSe Core-Shell Quantum Dots

In the present work CdTe/ ZnS, ZnSe, CdS, CdSe core-shell quantum dots were synthesized via co-precipitation route. The effect of reflux intervals from 1 to 7 hours, on the CdTe cores, characteristics such as: photoluminescence properties, band gap, structure, and microstructure were studied. Results showed that synthesis with the reflux time of 1 hour led to proper CdTe core with the size of about 4nm, emission wavelength of 555 nm, and band gap of 2.25 eV. More reflux time caused to particle size enlargement, emission shift to higher wavelength values, and band gap decrease. Moreover, ZnS, ZnSe, CdS, and CdSe shells were in-situ synthesized on the CdTe cores. Formation of these shells led to emission red shift with the wavelength up to 591 nm and band gap decrease to 2.15 eV.