A model for light induced effects in molecular conduction. The right and left manifolds represent the two metal leads characterized by electrochemical potentials and , respectively. The molecule is represented by its highest occupied molecular orbital (HOMO), ∣1⟩, and lowest unoccupied molecular orbital (LUMO), ∣2⟩.
The absorption current (photons/s), Eq. (40) or (41) for the molecular model of Fig. 1. The molecular electronic levels are assumed pinned to the right electrode, i.e., the bias shifts upward the electronic states of the left electrode. See text for parameters.
The photocurrent, Eq. (46), plotted against the incident light frequency in the absence of external potential bias. See text for parameters.
The source-drain current plotted against the voltage bias obtained from Eq. (46) in the presence of light. The parameters used are , , Fermi level taken halfway between and in the absence of bias , , , and . The bias is assumed to shift the energies of the molecular orbitals according to , , where in the present calculation we took and .
(a) The integrated photon emission rate (full line; red) and the source-drain current (dashed line; blue) displayed as functions of the bias voltage using , , (; ; ), , and . (b) Same as (a), except that . (c) The yield, plotted against the bias voltage for cases (a)—full line (red), and (b)—dashed line, blue.
Frequency resolved emission computed for the model of Fig. 1 using the parameters of Fig. 5(a), for different bias potentials.
The first derivative of the total emission intensity with respect to voltage (a) and the frequency resolved emission spectrum for a bias voltage (b). Full line (red)—parameters of Fig. 5(a). Dashed line (green)—same parameters except that and are taken larger by a factor of 3. Dotted line (blue) same parameters as in Fig. 5(a) except that (; ; ) are taken larger by a factor of 3. All lines were scaled to the same height. In (a) this requires a multiplicative factor of 1.62 on the dotted line and 2.10 on the dashed line and in (b) the factors are 1.35 and 0.99 on the dotted and dashed lines, respectively.
Photon emission from junctions characterized by different voltage division factors (see text). Full line (red) ; dashed line (green) ; and dotted line (blue) .
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