High temperature carrier mobility as an intrinsic transport parameter of an organic semiconductor

The high temperature limit of hole mobility (μ∞) in N,N′-diphenyl-N,N′-bis(1-naphthyl)(1,1′-biphenyl)-4,4′diamine (NPB) has been studied by time-of-flight technique. The effect of dopants on μ∞ was also investigated. It was found that the μ∞ is independent of the nature of dopants. The common μ∞ can be applied to estimate the full temperature dependence of zero-field mobility (μ0), if μ0 at one temperature is known. We demonstrate this concept by predicting the room temperature μ0 of NPB-doped with copper phthalocyanine (CuPc). The mobility prediction of CuPc-doped-NPB was then verified by the classic work of Hoesterey and Letson [D.C. Hoesterey, G.M. Letson, J. Phys. Chem. Solids 24 (1963) 1609].