Enhancing surface plasmon propagation and leakage in planar thin film and tubular metallic nanostructures for visible-light-based organic optoelectronics

Optical fields can be confined and propagated on subwavelength volumes by coupling to surface plasmon polariton (SPP) modes supported by metallic nanostructures. However, SPPs are inherently lossy modes, specifically in the visible regime with losses upwards of 1000 cm-1, resulting in short mode propagation lengths. SPPs are also a significant loss channel (up to 46.8% loss) in visible-light-based optoelectronics such as organic light-emitting diodes, significantly reducing light outcoupling efficiency.;Theoretical calculations in the literature have demonstrated that light-emitting organic semiconducting conjugated polymers can compensate for the intrinsic losses of SPPs. Engineering plasmon-polymer interactions may also aid in reducing loss at metal electrodes and increase light outcoupling efficiency in OLEDs. In this study, a fundamental understanding of efficient SPP/polymer emitter coupling, towards the development of low-loss electrodes for visible-light-based organic optoelectronics through the investigation of two distinct structures: (1) semiconductor-metal-insulator (SMI) waveguides and (2) tubular metallic nanostructures.;Dispersion relations were solved for the SMI waveguides over a range of metal film thickness and emitter dielectric constants. Solutions demonstrate that at visible wavelengths, SPP mode propagation lengths and magnetic field leakage are enhanced to lengths >1300 mum and >74 mum, respectively, through the optimization of the metal film thickness and by the addition of an organic polymer gain medium. These findings were experimentally validated by collecting pump power dependent emission spectra of SMI waveguides fabricated over a range of metal film thicknesses with controlled emitter dipole orientation.;Large area arrays of gold nanotubes were synthesized with wall thickness (WT) tuned from 30 nm to > 140 nm. Their optical response was characterized as a function of wall thickness and excitation condition via polarized bright-field/dark-field microscopy and darkfield scattered light spectroscopy. Resonant frequency, mode propagation length and mode type were found to be tunable based on tube geometry and excitation condition. Full-field 3-dimensional electromagnetic simulations were carried out to corroborate the experimental results and develop a fundamental understanding of the optical response of these structures for applications as low-loss patterned metal electrodes.