Surface plasmon-enhanced organic light-emitting devices

Abstract

Surface plasmons (SPs) resonances have hybrid nature that light wave trapped on the surface of conductor collectively interacts with the free electrons. One of most attractive features is to concentrate the light in subwavelength structures. Since the light concentration enhances an electric field, SPs can be used to light-matter coupling and achieve the sensor using nonlinear optical phenomena. Plasmonic applications driven by advances in surface-enhanced Raman spectroscopy, plasmon-mediated fluorescence emission, tip-enhanced fluorescence imaging and long-range absorption enhancement in organic thin film have been reported. Considering the recently emerging organic optoelectronics, plasmonic applications to the organic devices should be required for higher efficiency and sensitivity. The SP enhancement based on an organic light-emitting device (OLED) is reported in this thesis. For SP resonance, Ag nanoparticles were thermally evaporated in a high vacuum on cathode and 1-nm-thickness LiF spacer. Because SP provide a strong decay channel and surface emission in single organic molecule system, both time-resolved photoemission and continuous wave photoemission shows accelerating decay time and enhanced intensity, respectively. Additionally, the authors introduce an energy transfer enhancement in donor-acceptor system based on organic light-emitting device. SPs formed in the Ag nano cluster surface, provide strong donor decay channel, but also enhance the absorbance of acceptor. Enhanced energy-transfer improved the efficacy of OLED and has potential to apply into dye-doped laser, biosensor and other optoelectronic applications.