Charge separation and dissipation in molecular wires under a light radiation

Research paper by Hang Xie, Yu Zhang; Yanho Kwok; Wei E.I. Sha

Indexed on: 27 Apr '18Published on: 16 Apr '18Published in: Organic Electronics


Publication date: July 2018 Source:Organic Electronics, Volume 58 Author(s): Hang Xie, Yu Zhang, Yanho Kwok, Wei E.I. Sha Photon-induced charge separation in nanowires or molecular wires had been studied in previous experiments and simulations. Most researches deal with the carrier diffusions with the classical phenomenological models, or the static energy level calculations by quantum mechanics. Here we give a dynamic quantum investigation on the charge separation and dissipation in molecule wires. The method is based on the time-dependent non-equilibrium Green's function theory. Polyacetylene chain and poly-phenylene are used as model systems under a light pulse with the energy larger than the band gap. The dynamic transition and the dissipation processes of the non-equilibrium carriers are studied in these open nano systems. With the bias potentials or impurity atoms, the complicated charge separation process is also observed and discussed. Our calculations show that the separation speed of the electron/hole-type wave packets ranges from about 0.2 × 106 m/s to 0.6 × 106 m/s, and it may be reduced by the Coulomb interaction and an intensive radiation; and the asymmetric carrier separations are found due to the different effective masses of electron/hole of the molecular wire. Graphical abstract