Charge transport across organic-organic interfaces in organic light-emitting diodes

The process of hopping transport across organic heterojunctions is critical to the function of organic light-emitting diodes (OLED) and many other currently developed organic electronic devices. We consider the case of a hole-only or homopolar heterojunction with Gaussian energetic disorder. We cross-compare the results of our previous multiparticle Monte Carlo simulator to results of the pioneering analytic hopping model of Arkhipov et al. [VI. Arkhipov, EX Emelianova, H. Bassler, J. Appl. Phys. 90 (2001) 2352]. This comparison made it possible to point out and correct some shortcomings of the latter model. This includes the new definition of the injection level at the heterojunction, which brings orders of magnitude change to the current with respect to values obtained for previously used injection levels. Further insight, related to the backward-to-forward hopping ratio at the heterojunction, also brings about the order of magnitude correction for the current. We end up with a rather complete and cross-verified analytical description of the charge transport across energetically disordered homopolar heterojunctions. (c) 2006 Elsevier B.V. All rights reserved.