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(µ) ∝ 1/T^2 for the mobility µ. We demonstrate that in space-charge limited diodes the hole mobility (µh) of a large variety of organic semiconductors shows a universal Arrhenius temperature dependence µh(T) = µ0 exp(-Δ/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 µ0 of 30–40 cm2/Vs. As a result, we can predict the full temperature dependence of their charge transport properties with only the mobility at one temperature known.