Bipolarons In Polymers Research Articles

Photoinduced splitting of bipolarons in polymers

AbstractIn conducting polymers, a polaron carries charge with spin and a bipolaron carries charge without spin. Hence, the polaron is a spin carrier but the bipolaron is not. Through a dynamical simulation, our study of photoinduced phenomena shows that, by absorbing a photon, a bipolaron is split into two polarons. This photoinduced splitting converts a charge carrier (bipolaron) into two spin carriers (polarons). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Logical switching with the use of bipolarons in conjugated polymers

Considering impurity molecules functioning as switches, the charge transport on a single conducting polymer chain is investigated. The dynamics of structural bipolaron-type defects in conjugated polymers using a modified tight-binding hamiltonian is extended to include the effects of an external electric field and the parameters of the switching molecules are studied. The electric field is used to accelerate charged bipolarons in polymers and it is introduced in terms of a time-dependent vector potential. We use the Pariser–Parr–Pople model combined with the Su–Schrieffer–Heeger model of electron–lattice coupling and a Brazovskii–Kirova-type simmetry-breaking interaction. The process of charge transfer through the sites, and that it works like a switch, is analyzed by the numerical resolution of the equations of motion within the unrestricted Hartree–Fock approximation. The switching character of the parameters of the molecules on the charge transport through the chain is determined. The energies involved are also discussed.