Theoretical studies of P3HT, PQT, and PBTTT
There is considerable interest in soluble polymer semiconductors such as P3HT , PQT  and PBTTT . These materials have hole mobilities exceeding 0.1 cm2/Vs. As a consequence there is an impetus to determine the atomic and electronic structure of the crystalline lamellae exhibited by these materials. It remains a very challenging problem to determine the structure from experiment alone. Energy minimization calculations were therefore performed using the density functional theory to determine the atomic structure of these materials. A tilting of the plane containing the polymer backbone is found to be energetically favorable for all three materials. It is argued that this tilting is a general feature of this class of materials, and that this tilting has a significant affect on the electronic and optical properties. The impact of the deviation from ideal cofacial pi-stacking on the hole mobility will be discussed within a simple model of the scattering.
Northrup, J. E. Theoretical studies of P3HT, PQT, and PBTTT. 2007 MRS Spring Meeting; 2007 April 9-13; San Francsicso; CA.