Final answer:
Quantum dots are small regions of semiconductor nanocrystals that exhibit a change in color with size due to quantum confinement. The energy levels for electrons in quantum dots become quantized, resulting in a change in the wavelength of light emitted or absorbed by the quantum dot. This has applications in optoelectronics and nanotechnology.
Step-by-step explanation:
Quantum dots are small regions of semiconductor nanocrystals embedded in another semiconductor nanocrystal, acting as a potential well for electrons. These quantum dots exhibit interesting optical properties, including a change in color with size.
The change in color of quantum dots with size is due to quantum confinement. When the size of a quantum dot is small, the energy levels for electrons become quantized, meaning they can only exist at certain discrete energy levels. As the size of the quantum dot increases, the energy levels become closer together, resulting in a change in the wavelength of light emitted or absorbed by the quantum dot.
For example, smaller quantum dots may emit blue light, while larger quantum dots may emit red light. This phenomenon has applications in various fields, such as optoelectronics and nanotechnology.