Highly enhanced charge injection in thienoacene-based organic field-effect transistors with chemically doped contact

We describe the mechanism of contact resistance reduction and improvement in device performance of organic field-effect transistors by chemical doping at the contact interface. Insertion of iron(III)trichloride into the contact interface significantly reduced the contact resistance from 200 to 8.8 k Omega cm at a gate voltage of -40 V, and a field-effect mobility of 7.0 cm(2)/V s was achieved in devices based on dioctylbenzothienobenzothiophene. The improved charge injection is attributable to a reduction in the depletion layer thickness at the contact interface and occupation of trap states in the access region due to the generation of charge carriers by contact doping. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3690949]