Abstract-Band Transport and Trapping in Didodecyl[1]benzothieno[3,2-b][1]benzothiophene Probed by Terahertz Spectroscopy

Thomas Rene Arend, Andreas Wimmer, Guillaume Schweicher, Basab Chattopadhyay, Yves Henri Geerts, and Roland Kersting

http://pubsdc3.acs.org/doi/10.1021/acs.jpclett.7b02304

Terahertz electromodulation spectroscopy provides insight into the material-inherent transport properties of charge carriers in organic semiconductors. Experiments on didodecyl[1]benzothieno[3,2-b][1]benzothiophene (C12-BTBT-C12) devices yield for holes an intra-band mobility of 9 cm2 V-1 s-1. The short duration of the THz pulses advances the understanding of the hole transport on the molecular scale. The efficient screening of Coulomb potentials leads to a collective response of the hole gas to external fields, which can be well described by the Drude model. Bias-stress of the devices generates deep traps that capture mobile holes. Although the resulting polarization across the device hinders the injection of mobile holes, the hole mobilities are not affected.