Current voltage relation of amorphous materials based pn diodes—the effect of degeneracy in organic polymers/molecules

A general representation of the current in an amorphous semiconductor pn diode is developed. This expression is applied to examples of density of states functions exponential, Gaussian, and Gaussian with exponential tail commonly found in conjugated molecules and other amorphous materials. We find that the ideality factor could be voltage dependent and that its functional form is closely related to the shape of the density of states. © 2009 American Institute of Physics. doi:10.1063/1.3245283