Doping effects on charge transport in organic materials
K. Leo and M. Hummert, Technische Universität Dresden, Germany
In this chapter, we review recent basic work on molecular doping of organic semiconductors. We focus on doped layers prepared by co-evaporation in vacuum, which are utilised in highly efficient organic light-emitting diodes and organic solar cells. Various doping materials are compared, as well as their evaluation in devices. The fundamental processes during doping and the effort on layer properties are presented. Doping of organic semiconductors offers two striking advantages: The conductivity can be controlled and enhanced for orders of magnitude. Secondly, the Fermi energy levels are shifted towards the ...