Thickness scaling of space-charge-limited currents in organic layers with field- or density-dependent mobility

An exact solution is provided for the current density-voltage (J-V) characteristics of space-charge limited transport of a single carrier in organic layers with field-dependent mobility of the type mu(E) = mu(0) exp (gamma root E). The general scaling relationship for field-dependent mobility occurs in terms of the variables JL and V/L. For the density-dependence of the mobility found in organic field-effect transistor measurements, the thickness scaling occurs in terms of different variables, J(1/B)L and V/L. The proposed scaling is a useful test for distinguishing field- and carrier density-dependent mobility in disordered organic semiconductors. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.