Structural and dynamical characterization of P3HT/PCBM blends

- First quasi-elastic neutron scattering data on P3HT-PCBM blends.
- PCBM slows down the dynamics in P3HT.
- Blend from chlorobenzene shows significant degree of order in its “pristine” (as cast) state.
- Blends prepared from choroform and dichlorobenzene develop their order upon annealing.
- P3HT dynamics in the blend system are independent on solvent.

We report data from X-ray and neutron scattering on the structure and dynamics of P3HT-PCBM solid blends cast from three different solvents, characterized by different boiling points, namely chloroform (CF, boiling point Tb = 61.2 °C), chlorobenzene (CB, Tb = 131 °C) and ortho-dichlorobenzene (ODCB, Tb = 180.5 °C). Whereas the blend cast from CB shows already a significant degree of order in its “pristine” (as cast) state, blends prepared from CF and ODCB develop their order only upon annealing at 160 °C. In addition, blending seems to frustrate the polymer dynamics. We propose that such change in dynamics might be related to the polymer confinement within PCBM domains. However, no appreciable difference in the degree of dynamics (and/or of its frustration) is observed as a function of the solvent choice.