Dynamics of Quasiparticles Generation, Transport and Relaxation in Armchair-edge Graphene Nanoribbons

摘要

We study the dynamics of quasiparticles such as quasiparticles generation, charge transport and relaxation in armchair-edge graphene nanoribbons of the ribbon width of six carbon atoms by numerical simulation. A polaron is created by hole injection into HOMO of the ribbons while a self-trapped exciton is created by photoexcitation of an electron from the HOMO to the LUMO. The dynamical simulations after hole injection or photoexcitation have revealed that phonon fluctuations are necessary for the quasiparticles to be generated. The creation time becomes shorter as the amplitude of the phonon fluctuations increases. The polaron transport in the presence of a bond-type defect is also investigated. It is found that the transmittance and the reflectance of the polaron depend on the position of the defect as well as the strength of the applied electric field. Under particular conditions, the polaron may be split into fractions even though it is an elementary excitation. As for the exciton relaxation, it is found that the exciton leaves oscillations of the bond distortion after photon emission. The oscillations are localized in space and quasi-periodic in time and therefore correspond to a breather or an intrinsic localized mode known to exist in nonlinear differential equations and also in conducting polymers.