DISORDERED DISTRIBUTION OF DEFECTS IN POLYTHIOPHENE

In this work we study the electronic structure associated to a disorde red distribution of bipolarons in polythiophene. The polymer chain is modelled by a tight-binding Hamiltonian with explicit treatment of ele ctron-phonon coupling and the elastic energy of the sigma framework. T he model also includes the electrostatic interaction due to the counte rions. The density of states of the disordered system is obtained by t he use of the Negative Factor Counting technique. Our results show tha t ion-induced conformational disorder can account for the closure of t he gap and that the states around the Fermi level are extended.