External field control of charge transmission through single molecules: Switching effects and transient currents

Photoinduced Anomalous Coulomb Blockade and the Role of Triplet States in Electron Transport through an Irradiated Molecular Transistor

“…The optical field is modeled in eq as a periodically oscillating electric field E ( t ) = E 0 ( e iωt + e – iωt ) with amplitude E 0 and frequency ω. Its interaction with the transition dipole moment d 01 of the states | 0, S 0 ⟩ and | 0, S 1 ⟩ leads to the stimulated absorption and emission processes, whose rates, k 0, S 1 ← 0, S 0 field and k 0, S 0 ← 0, S 1 field , are equal in magnitude and given by , where the energy gap is ℏω 10 = E 0, S 1 – E 0, S 0 and the broadening κ 0 S 1 ,0 S 0 is caused by the electron transfer processes between the neutral singlet states and the other charged states. , For simplicity, we denote the rate k 0, S 0 ↔0, S 1 field as k field from now on. The rate of spontaneous emission process k 0, S 0 ← 0, S 1 spon is considered in our model phenomenologically and calculated as − , where α is the fine structure constant, n is the refractive index, and c is the speed of light in vacuum.…”

“…where the energy gap is ℏω 10 = E 0,S 1 − E 0,S 0 and the broadening κ 0S 1 ,0S 0 is caused by the electron transfer processes between the neutral singlet states and the other charged states. 50,72 For simplicity, we denote the rate k 0,S 0 ↔0,S 1 field as k field from now on. The rate of spontaneous emission process k 0,S 0 ← 0,S 1 spon is considered in our model phenomenologically and calculated as 73 The parameters employed in our simulations are listed in Table 1.…”

Molecular optoelectronics: the interaction of molecular conduction junctions with light

“…This is often the case in voltage induced switching of redox molecular junctions, 53 and can be induced photochemically as well. [54][55][56][57][58][59] On the theoretical side, Wang and May 60,61 have addressed the problem of electronic switching by considering the dynamics of electronic transitions in the molecule and in the metal electrodes, in conjunction with the conduction properties of the molecular bridge in its ground and excited states, taking into account electronic-vibrational coupling and vibrational heating.…”

“…91,92 Alternatively, several workers have used the master equation approach or similar kinetic descriptions of junction transport, again generalized to take into account the effect of an external time dependent field. Calculations involving time-periodic fields are facilitated by using Floquet's theory 68,101 (see references to other papers by the Ha¨nggi group in these review articles), and a simplified description may be achieved by invoking the rotating wave approximation, 60,61,[102][103][104][105][106][107] but general time dependence of the external field, applicable to pulse excitations, has been addressed as well [108][109][110][111][112][113][114][115][116][117] at the cost of more involved numerical work. Such an approach relies on the assumption of weak molecule-lead coupling, which may be sufficient in some situations but can miss important physical effects in others.…”

Photoinduced anomalous Coulomb blockade and the role of triplet states in electron transport through an irradiated molecular transistor. II. Effects of electron-phonon coupling and vibrational relaxation

“…Electron-vibration interactions exhibit rich physical phenomena in nanoscale electron transport and inspire extensive theoretical studies. 59,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] Among these studies, we would like to emphasize the pioneering works by Koch [76][77][78]85 and May 59,[79][80][81][82]86,87 . Koch et.…”