CHARGE-TRANSFER STATES IN POLYACENE CRYSTALS

The role of charge transfer states in theoretical interpretation of spectroscopic experiments on polyacene crystals in electric field (photocurrent and electroabsorption) is discussed. A crude estimate suggests that while the low energy part of the photocurrent spectrum is probably dominated by CT states generated by direct optical absorption, at higher energies Frenkel exciton autoionization is likely to prevail. For electroabsorption, the notion of CT state degeneracy as a possible reason of the second derivative contribution is examinded on a simple dimer model.