Effect of host organic semiconductors on electrical doping

The effect of host organic semiconductors on electrical doping has been investigated. Electrical conductivities and carrier densities in various hosts are increased by doping with ReO3. The degree of carrier generation by the p-doping is, however, different for different host organic semiconductors and depends on the energy difference between the HOMO level of the hosts and the Fermi energy level of the dopant (Delta E = E-HOMO,E-host - E-F,E-dopant). The larger Delta E resulted in increased carrier generation. In contrast, hole mobilities were reduced by the doping if the organic semiconductors are heavily doped with a doping concentration of 25 mol%. The reduction of the mobilities is also different for different organic semiconductors and is not inversely proportional to the generated carrier densities. (C) 2009 Elsevier B.V. All rights reserved.