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/T² 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)=μ₀exp(-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/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.