ULTRAFAST ELECTRONIC AND VIBRATION DYNAMICS OF PHOTOVOLTAIC POLYMER P3HT IN NON-POLAR AND POLAR SOLVENTS

摘要

In our previous work, ultrafast relaxation dynamics of photoexcitation in poly(3-hexylthiophene) (P3HT) film was studied to determine the defect concentration. The present work was performed to study ultrafast dynamics of the P3HT solutions in various solvents. The ultrafast dynamics was studied by using ultrashort sub-10fs pulse, which resolves not only the electronic dynamics but also the vibration dynamics. The electronic dynamics show fast and slow relaxations with time constants of ～200fs and ～3ps, respectively. The faster time constant (～200fs) is thought be the speed of intrachain charge transfer to form a bound polaron pair in the P3HT chain, and the time constant is longer when the dipole moment of the solvent is larger. The slower time constant (～3ps) reflects the relaxation of the polaron pair also showing similar dependence on the dipole moment of the solvent. Linear prediction singular value decomposition method was used to estimate life time of the vibration modes. The dependence on the dipole moment of the solvent was opposite in the vibration lifetime compared with that in the electronic state lifetime. It shows that the vibration mode has strong interaction with the electronic excited state when the dipole moment of the solvent is large.