Same Charge Polaron and Bipolaron Scattering on Conducting Polymers

Abstract

We study the dynamics of scattering of two positive polarons moving toward each other with parallel spins and of a polaron and a bipolaron both with positive charges and different velocities, in single chains of cis-polyacetylene and polyparaphenylene. We use the Su−Schrieffer−Heeger model with Hubbard extensions solved within of the time-dependent Hartree−Fock approximation to account for electron−electron interactions, developed over a hexagonal lattice. The main results are elastic scattering in most cases. This behavior changes to transmission of the polaron through the bipolaron when the ratio of their velocities in the same direction is in the range of 3:1 to 5:1 when no external electric field is present. The velocities ratio changes to of 6:1 to 8:1 under external electric field. This suggests that these systems may present an abrupt increase in the charge transport, under specific conditions, in an otherwise smoothly and monotonically increasing relation to the applied field. Their effective masses in these systems are also determined: the polaron effective mass is 4−8 times the rest mass of a free electron, and that of the bipolaron is 15−30 times the electron mass.

Strain-Tuneable Bipolaron Stability on Ultranarrow Bilayer Graphene Nanoribbon

“…Previous studies have shown that the carrier size imposes influence over transport capabilities. 34,51,52,62 For GNRs and conjugated polymers, wider quasiparticles are likely to be more mobile than strongly localized carriers. Here, we extend this reasoning.…”

“…Such behavior is characteristic of conjugated materials. The pivotal implication is that bipolarons tend to possess a greater effective mass in comparison to polarons. , This behavior is expected to persist in the B4A system.…”

Spin Hall effect from bipolaron dynamics in organics

“…It is natural since the effective mass of the bipolaron is about four times that of the polaron. 52,53 A small amount of charge transfers to the two edge chains (chain 1 and chain 3) and also moves periodically.…”

Intrinsic Properties of Bipolarons in Armchair Graphene Nanoribbons

“…With such a description in hand, we can now investigate the relationship between the effective mass of the bipolaron in the system ( ) and the electron-phonon coupling as well as to the electric field. For the calculation of the effective mass, we considered the same scheme as employed for the calculation of the effective mass of the polaron and bipolaron in cis-polyacetylene and poly-pphenylene (PPP) [49], i.e., the equality between impulse and linear momentum variation (Δ ⃗ = ⃗ Δ ). The electric field was turned on adiabatically so that to avoid artificial numerical effects [50].…”