Dynamics of photogenerated charge carrier and morphology dependence in polythiophene films studied by in situ time-resolved microwave conductivity and transient absorption spectroscopy

For the investigation of photoconductivity and charge carrier dynamics in regioregular poly(3-hexylthiophene) (RR-P3HT), an in situ flash-photolysis time-resolved microwave conductivity (FP-TRMC) and transient absorption spectroscopy (TAS) was performed using 6.4 and 3.5 eV photon excitation. Since the former energy is sufficiently higher than ionization potential of RR-P3HT, a direct ionization and consequent bulk charge recombination was observed. The dynamics of charge carriers of transient conductivity and photoabsorption kinetics are discussed in terms of the X-ray diffraction pattern and film morphology of RR-P3HT observed by tapping mode atomic force microscope.