Effects of metal film thickness and gain on the coupling of organic semiconductor exciton emission to surface plasmon polaritons

Abstract

This work presents an experimental investigation of enhancing surface plasmon polariton coupling to semiconductor emission by tailoring metal film thickness.

Strong Plasmon–Exciton Coupling in Ag Nanoparticle—Conjugated Polymer Core-Shell Hybrid Nanostructures

“…As with prior reports on plasmon-enhanced conjugated polymer structures [ 30 , 43 , 44 , 45 , 46 , 59 , 60 , 61 , 77 ], we observed the largest absorption enhancement in the conjugated polymer shell at wavelengths red-shifted from the absorption of the uncoupled polymers ( Figure 7 d–f). This red-edge absorption enhancement, which has been frequently reported in the literature, can now be attributed to the long wavelength hybrid mode of a coupled plasmon–exciton system.…”

“…There have been a few recent theoretical studies demonstrating that vibrationally-dressed excitonic states can strongly couple with microcavities [ 40 , 41 , 42 ]. We have previously demonstrated coupling between excitons in conjugated polymers and surface plasmons arising from metasurfaces [ 43 , 44 ], nanoparticle-on-mirror [ 45 ], and semiconductor-metal-insulator waveguide [ 46 ] geometries. Additionally, it has been demonstrated that when plasmonic nanostructures are embedded into broadband, conjugated polymer-fullerene photovoltaic absorber layers that the largest absorption enhancements occur at wavelengths slightly red-shifted from the absorption edge of the absorber (i.e., at the “red-edge”) [ 43 , 47 , 48 , 49 , 50 , 51 , 52 ].…”

Photon Recycling in Semiconductor Thin Films and Devices

“…It was found that the edge emission behavior from the waveguides depended on both the Ag film thickness and roughness. [ 101 ] The shape of the emission spectra showed clear signatures of reabsorption of shorter wavelength emission similar to what occurs in PR.…”

“…Edge emission measurements, also known as cutoff emission measurements, are used to study a boundary phenomenon between the cases where light is guided and where light is leaky, which means that the incident angle in a thin film θ 2 corresponds to the critical angle of the waveguide θ c ( Figure 6 a ). [ 96 , 97 , 98 , 99 , 100 , 101 ] Edge emission measurements are also capable of detecting guided modes (i.e., when θ 2 > θ c ). At the cutoff wavelength for the waveguide, the angle for propagation will be equal to the critical angle for the active material/glass interface and no total internal reflection will occur.…”

“…[ 92 ] In the past decades, edge emission measurements were important methods to study amplified spontaneous emission (ASE) in high‐gain conjugated polymer films. [ 97 , 98 , 99 , 100 , 101 ] In these studies, photons emitted inside the polymer films are guided to the sample edge. Edge emission measurements have the potential to be used to characterize PR because of the collection of emission that is trapped in propagating modes.…”