Control of localized surface plasmon resonance of Ag nanoparticles by changing its size and morphology

Abstract

Ag thin-films with thicknesses of 5, 10, 15, 20, and 25 nm are deposited by thermal vacuum evaporation, and the obtained films are subsequently annealed at 400 °C for 1 h to form the Ag nanoparticles (NPs). The averaged diameters of the resultant Ag NPs are increased from 50 to 300 nm as increasing the initial Ag deposition thickness, according to the morphological observation using scanning electron microscopy (SEM). The significant red-shift of the extinction peak depending on the particle size of the Ag NPs, which can be assigned to the localized surface plasmon resonance of the Ag NPs. The organic emitter, tris(8-hydroxyquinolinato)aluminum (Alq3) film is overcoated on the Ag NPs. About 4-fold enhancement of the photoluminescence of Alq3 was observed in combination with the larger size Ag NPs fabricated from the 15–25 nm thick Ag films, which can be applied for the improvement of the light-extraction efficiency of the organic light-emitting devices.