Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 99: Organic Semiconductors: Transport

HL 99.4: Talk

Friday, March 30, 2012, 10:15–10:30, EW 203

Multiscale simulations of the density of states, DC and terahertz mobility of charge carriers in disordered conjugated polymers — •Nenad Vukmirovic — Scientific Computing Laboratory, Institute of Physics Belgrade, University of Belgrade, Serbia

Understanding the relationship between the atomic structure of an organic material and its electrical properties is of utmost importance for the development of materials for organic electronic devices. In this work, recently developed simulation frameworks [1,2,3] were used to understand the factors that determine the density of states, the DC and the terahertz mobility of several materials.

It was found that the size of the torsion barrier between neighbouring polymer units strongly affects the density of electronic states and consequently all electrical properties. Next, it was shown that alkyl chains act not only as insulating barriers that impede the transport but their presence may also reduce the disorder caused by other chains and consequently enhance the transport. Finally, the simulations also give insight into the distribution of carrier energies and transport distances that are probed in measurements of the mobility at terahertz frequencies. Their fingerprint is much weaker dependence of the terahertz mobility on temperature in comparison to the DC case.

[1] N. Vukmirovic and L.-W. Wang, J. Phys. Chem. B 115, 1792 (2011). [2] N. Vukmirovic and L.-W. Wang, Nano Lett. 9, 3996 (2009). [3] N. Vukmirovic and L.-W. Wang, J. Phys. Chem. B 113, 409 (2009).