Single-step light-assisted patterning of photonic properties of chemical-bath-deposited CdSe nanocrystalline films

We report on the effect of light illumination of nanocrystalline CdSe film during its deposition from chemical bath. We concentrate on the photoexcited carrier dynamics studied by techniques of ultrafast laser spectroscopy. Light illumination by above-band gap light during the growth leads to larger nanocrystals (NCs), which means that the single-step nanocrystal size patterning (with the spatial resolution of tens microns as given by illumination light masking) is possible. Nanocrystal size is a dominating factor, which affects the properties of the films, namely absorption, photoluminescence (PL), and the photoexcited carrier dynamics. The properties are further influenced by the interplay between the interior and surface states of nanocrystals, which is affected by the nanocrystalline size and/or by their surface quality.