At the nanoscale, the high surface area-to-volume ratio means that surface atoms play a significant role in determining the optical properties of the material. Surface states and defects can introduce localized electronic states within the bandgap, affecting the material's optical behavior. These states can act as traps for charge carriers, influencing processes like photoluminescence and non-radiative recombination. Controlling these defects and surface states is crucial for optimizing the optical performance of nanomaterials.
