Colloidal quantum dots (CQDs) are nanocrystals that can be used to make various electronic devices. They are semiconductor crystals with a diameter of less than 20 nanometers. CQDs are made from a variety of materials, including CdSe, InP, PbS, and PbSe. The unique property of CQDs: quantum confinement effect: The optical and electrical properties of CQDs can be tuned by changing their size and shape. Therefore, the bandgap of CQDs can be adjusted by changing their size from visible to infrared wavelength for absorption and emissio