Theoretical Study on the Absorbance Bandgap of the Group II-VI Semiconductor Quantum Dots

A theoretical study on the absorbance bandgap of the CdSe, CdS and ZnS QDs has been studied using effective mass approximation. The results strongly indicate that the quantum confinement effect on QDs leads to a size-dependent increase in the absorbance bandgap. This property allows for the tuning of optical and electronic characteristics, making these materials highly valuable in various advanced technological applications. It is found that CdSe with a bulk bandgap of ~1.7 eV increases as the dot size decreases, resulting in a shift from red to blue emission; CdS begins at ~2.42 eV and increases as the size decreases, shifting from green to violet emission and ZnS with largest initial bandgap of ~3.68 eV is pushed further into the UV range as the size decreases. Thus, by controlling the size of the QDs, it is possible to precisely tailor their properties for specific uses, making them highly versatile for a range of applications in optoelectronics, biomedical imaging, and quantum computing.