Universal arrhenius temperature activated charge transport in diodes from disordered organic semiconductors

Charge transport models developed for disordered organic semiconductors predict a non-Arrhenius temperature dependence ln(mu) proportional to 1/T(2) for the mobility mu. We demonstrate that in space-charge limited diodes the hole mobility (mu(h)) of a large variety of organic semiconductors shows a universal Arrhenius temperature dependence mu(h)(T) = mu(0) exp(-Delta/kT) at low fields, due to the presence of extrinsic carriers from the Ohmic contact. The transport in a range of organic semiconductors, with a variation in room temperature mobility of more than 6 orders of magnitude, is characterized by a universal mobility mu(0) of 30-40 cm(2)/V s. As a result, we can predict the full temperature dependence of their charge transport properties with only the mobility at one temperature known.