Highly bright and sharp light emission of a single nanoparticle of crystalline rubrene

Abstract

We report on the fabrication and nanoscale luminescence characteristics of an isolated rubrene single nanoparticle (NP). A solvent-vapor annealing process changed pristine rubrene NPs, prepared by a reprecipitation method, to perfect crystalline NPs. The formation and structural properties of crystalline and non-crystalline rubrene NPs were studied through SEM, HR-TEM, and X-ray diffraction experiments. The nanoscale photoluminescence (PL) characteristics and the luminescence color of the rubrene single NP were measured using a high-resolution laser confocal microscope with color charge-coupled device images. In comparison with the pristine rubrene NPs, the crystalline NPs exhibited highly bright and sharp light emission. The main PL peak at 561–562 nm for the crystalline rubrene single NP had a relatively narrow line-width and became more dominant through a solvent-vapor annealing. The enhanced and sharp light emission of the crystalline rubrene single NP originated from the strong π–π interaction of rubrene molecules along the major crystalline axis in the nano-sized structure.