Browsing by Author "Lee, Yu Hsien"

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Ultrafast relaxation dynamics of photoexcitations in poly(3-hexylthiophene) for the determination of the defect concentration
(2010-09-30)
Lee, Yu Hsien
;
Yabushita, Atsushi
;
Hsu, Chain Shu
;
Yang, Sheng Hsiung
;
Iwakura, Izumi
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. (C) 2010 Elsevier B.V. All rights reserved.
Ultrafast spectroscopy of poly-thiophene derivative by using sub-10 fs visible pulse
(2012)
Yabushita, Atsushi
;
Lee, Yu Hsien
;
Hsu, Chain Shu
;
Yang, Sheng Hsiung
;
Luo, Chih Wei
Ultrafast spectroscopy was performed for a poly(3-hexylthiophene) (P3HT) film changing pump power. The result clarified the femtosecond time constant for generation and relaxation of the bound polaron pair in the film. (C) 2010 Optical Society of America