Fig. 1: Optoelectronic properties of quantum dots under UV light irradiation.

a Band structure of a quantum dot (QD). Unlike bulk semiconductors, nanocrystals exhibit discrete energy levels within their bands. When photons excite charge carriers from the lowest energy levels (valence band) to higher energy levels (conduction band), relaxation can result in photoluminescence or charge trapping at surface states. Adapted from ref. ¹. Copyright 2021, American Chemical Society. b Schematic illustration of the quantum confinement effect on the photoluminescence of QDs of different sizes. When a solution of free QDs is exposed to UV light, the emission color depends on nanocrystal size; larger QDs emit red light and smaller QDs blue light.