Electrochemical methods coupled with impedance measurement for energy gap study: correlation between the energy states and charge transport properties

The energy states of poly(3-hexylthiophene) (P3HT) polymer films degraded using UV/ozone environment were studied by optical and electrochemical methods. Energy levels of highest occupied and lowest unoccupied molecular orbitals as well as localized states between them were estimated. Electrical properties of polymer films sandwiched between two metal electrodes were investigated for various trap energy distributions. Comparison of the energy states density evaluated by optical/electrochemical methods and estimated from the current-voltage characteristics was carried out to discuss suitability of space-charge limited electrical conduction models for semiconducting polymers.