Morphology-Dependent Carrier and Exciton Generations in Regioregular Poly(3-hexylthiophene) Polymer Diodes as Revealed by Bleaching Spectroscopy

Bleaching probe spectroscopy performed for regioregular poly(3-hexylthiophene) diodes reveals that coexistent morphological phases determine the conducting and optical properties of conjugated polymer films. Photoinduced absorption measurements demonstrate that exciton migration occurs from lamella aggregates to morphological sites consisting of quasiuncoupled chains and that the latter sites determine steady-state photophysical properties. Spectroscopy synchronized with diode operation reveals that the morphological locations of injected carriers in polymer diodes vary with the applied bias.