INTRACHAIN PHOTOCONDUCTIVITY OF CONJUGATED POLYMERS FROM POLARON PAIRS

For a one-dimensional model of conjugated polymers, we show that the absorption of the light polarized along the chain may cause the production of not only conventional kink-antikink pairs but also of free polaron pairs. The latter pairs provide a fast photocurrent even in nondegenerate-ground-state polymers. The system can be excited into an Ag-symmetric polaronic state because of the violation of the parity-symmetry selection rule at optical transitions as well as owing to losing the memory of the electronic parity during the electron-hole relaxation. © 1990.