The electrostatic capacitance-voltage characteristics of single and double layer organic diodes are explored by numerical simulation and theoretical analysis. For single layer devices, the capacitance in the high voltage limit is approximately 3/2 times the geometric capacitance C 0 for unipolar carrier injection or ambipolar injection with high recombination rates, and 4/πC 0 for symmetric ambipolar injection with low recombination rates. For double layer devices, the capacitance is determined by the relative charge distribution at the contacts, in the bulk region of the two layers, and at their interface. The charge distribution is affected by the injection barrier height and by exciplex-controlled interface recombination.
Bibliographical noteFunding Information:
This work was supported in part by a University of Minnesota Graduate School Fellowship. Additional support was provided by the MRSEC Program of the National Science Foundation under Award No. DMR-0819885. Work at Los Alamos National Laboratory was supported by the LDRD program. Access to the facilities of the Minnesota Supercomputing Institute is gratefully acknowledged.