Gme. Silva, Electric-field effects on the competition between polarons and bipolarons in conjugated polymers, PHYS REV B, 61(16), 2000, pp. 10777-10781
The charge transport on a single conducting polymer chain is investigated.
The dynamics of polarons and bipolarons is numerically studied using the Su
-Schrieffer-Heeger model combined with the Pariser-Parr-Pople model extende
d to include an external electric field and a Brazovskii-Kirova symmetry br
eaking interaction. The time-dependent unrestricted Hartree-Fock approximat
ion is used. It is found that dynamical effects do not reverse the stabilit
y relation between polarons and bipolarons. On the other hand, as the elect
ric held intensity gets stronger the moving polarons structure is blurred (
destroyed) faster than the structure of moving bipolarons. This effect is r
educed with increasing doping concentration. Therefore, it is shown within
the present model that the applied external electric field as well as the d
oping concentration are fundamental in determining the relative prevalence
of polarons or bipolarons.