Figure 3
From: Signatures of Plexcitonic States in Molecular Electroluminescence
The calculated STML of a TPP molecule coupled to a single plasmon mode is shown as a function of photon energy for four plexcitonic coupling strengths \(\hslash {g}_{00}\) = 0 meV, 10 meV, 20 meV, and 30 meV at three bias voltages Vb = 1.8 V, 1.9 V, and 2.5 V. In the decoupled cavity limit (\(\hslash {g}_{00}=0\) meV), the molecular vibrational spectrum is recovered. As g11 is increased plexcitonic states begin to form, giving rise to the characteristic split peak structure in the EL. Although all radiative transitions have non-zero coupling to the plasmonic field, the resonant Q(0,0) transition dominates and the plexcitonic splitting is \(\sim 2\hslash {g}_{00}\). The coherent mixing of multiple states gives rise to the asymmetric peak structure and the above threshold hot HL observed when Vb = 1.8 V; even for junctions operating in the weak coupling regime. For this system, the strong coupling boundary is \(\hslash {g}_{00} > \sim \) 15 meV. Calculations are for junctions operating at T = 80 K, to be consistent with measured STML spectra18.
