Acta Electronica Malaysia (AEM)

Quantum dots are semiconductors whose exciton (electron-hole pairs) experience quantum confinement in all three spatial dimensions. As a result, they have properties that are between those of bulk semiconductors and those of discrete molecules. This confinement dramatically alters the optical properties of these dots as compared to the bulk material having applications in transistors, light-emitting diodes (LEDs), laser diodes, sensor devices, telecommunication, biophysics and photovoltaic devices. In this work, Zinc oxide quantum dots were synthesized via the wet chemical colloidal synthesis method at 65 °C using zinc acetate, sodium hydroxide and isopropanol. The optical absorption properties of the synthesized Zinc oxide quantum dots were studied and it was found that the quantum dots absorbed light in the wavelength range of 200-800 nm with maximum absorbance value of 250-300 nm. The energy band gap of the synthesized ZnO quantum dots varied from 3.81-4.07 eV depending on the size of the sample. The size of the prepared quantum dots were found to be 3.2 nm, 3.6 nm and 4 nm for ageing time of zero second, 300 seconds and 600 seconds with a calculated band gap energy of 4.07 eV, 3.90 eV and 3.81 eV respectively. The optical spectra revealed that there was a narrow size distribution and a blue shift in the energy band gap which indicated that the ZnO quantum dots exhibited a strong confinement effect.