  The ratio between mobility and diffusion parameters is derived for a
Gaussian-like density of states. This steady-state analysis is expected to be
applicable to a wide range of organic materials (polymers or small molecules)
as it relies on the existence of quasi-equilibrium only. Our analysis shows
that there is an inherent dependence of the transport in trap-free disordered
organic-materials on the charge density. The implications for the contact
phenomena and exciton generation rate in light emitting diodes as well as
channel-width in field-effect transistors is discussed.
