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- redrum
- Semiconductor nanocrystallites (quantum dots, QDs) whose radii are smaller than the bulk exciton Bohr radius constitute a class of materials intermediate between molecular and bulk forms of matter. Quantum confinement of both the electron and hole in all three dimensions leads to an increase in the effective band gap of the material with decreasing crystallite size (Figure 1). Consequently, both the optical absorption and emission of quantum dots shift to the blue (higher energies) as the size of the dots gets smaller. Although nanocrystallites have not yet completed their evolution into bulk solids, structural studies indicate that they retain the bulk crystal structure and lattice parameter. Recent advances in the synthesis of highly monodisperse nanocrystallites have paved the way for numerous spectroscopic studies assigning the quantum dot electronic states and mapping out their evolution as a function of size.
