Ultrafast relaxation dynamics of photoexcitations in poly(3-hexylthiophene) for the determination of the defect concentration

作者：Lee Yu Hsien^*; Yabushita Atsushi; Hsu Chain Shu; Yang Sheng Hsiung; Iwakura Izumi; Luo Chih Wei; Wu Kaung Hsiung; Kobayashi Takayoshi

来源：Chemical Physics Letters, 2010, 498(1-3): 71-76.

DOI：10.1016/j.cplett.2010.08.036

Ultrafast pump-probe spectroscopy of poly(3-hexylthiophene) (P3HT) films was performed using a 9-fs laser and a broadband lock-in detection system. The fast geometrical relaxation (GR) time was attributed to the transition from a free exciton (FE) to form a bound polaron pair (BPP), and the time constant was estimated to be tau(GR) = 90 +/- 2 fs. The relaxation time constant of BPP was determined as tau(BPP) = 710 +/- 40 fs. The measurement of pump-power dependence enabled us to distinguish the defect trapping process of BPPs from other parallel decay processes and to determine the defect concentration of a P3HT thin film.