Green Synthesis and Evaluation of Electronic and Optical Properties of CdS/CdTe Quantum Dots

The CdS/CdTe quantum dots (QDs), with altered concentrations of CdS, were synthesized using straightforward precursors through an environmentally friendly green method. The synthesized quantum dots were characterization by UV-visible absorption spectroscopy, Photoluminescence (PL), and Fourier Transform Infrared Spectroscopy (FTIR) to understand their electronic and structural properties. The average particle size is nearly consistent with the values derived from Brus's formula. The UV-visible spectra show a blueshift compared with pure sample, this could be attributed as quantum size effect on electron and hole. The band gap energy ranges from 2.71 eV to 2.32 eV indicating tunable optical properties. Band gap energy decreases as the size of quantum dots increasing. The band gap energy of system was determined from absorption data, using a Tauc plot, yielding a value of 2.71 eV. The FTIR showed a significant vibrational peak near 732 cm-1, indicating the presence of the Te-O and carbonyl group C=O. The estimated band gap of CdS/CdTe based quantum dots, determined through Tauc plot analysis, is 2.59 eV. The PL emission peak range from 500-650 nm show size dependent of optical properties. The PL spectra show a strong and narrow emission peak, indicating high quantum efficiency. The preset work is aimed to enhance the characteristics of CdTe/CdS properties suitable for energy conversion and to further stimulate interest, as the emission of CdS/CdTe QDs exhibits peaks positioned at 608 nm, attributed to the presence of cadmium ions vacancies align qualitatively.