Optical properties of different crystal structures under evaporative crystallization

Abstract We investigate the behavior of evaporative crystallization of a fluorescent dye droplets on the substrates with different contact angles. Evaporation of the dye drop lead to smaller crystals at the centre of the droplet. In the case of on the glass substrate, two distinct microcrystalline morphologies of the recrystallized deposits – hexagonal and stick/rod shaped have been observed. This indicates that the evaporation driven crystallization is highly dependent on the wettability of the substrate. The sizes of crystals decrease on increasing the contact angle of the substrate. The photoluminescence (PL) studies indicate that the hexagonal crystals have higher emission compared to rod-shaped crystals. PL decay measurements also show distinct lifetimes for the two shapes. The self-assembly leading to the formation of distinct crystal morphologies along with their individual optical properties different from the parent material is highly interesting to the optical materials research.