We present a microscopic theory of charge transport and electrode injection in otganic light emitting diodes which accounts for most of the molecular aspects of these materials.The rational optimization of classical semiconductor optoelectronics devices required a good knowledge of the basic transport and light emission processes. The same work should be done in organic devices where charge transport and electrode injection stand as a crucial points for device optimization.Until now, most of the transport models used in organic light emitting diodes are directly derived from the semiconductor physics of analogous silicon devices [1, 2].We believe that the physics of transport and charge injection is very different in molecular and polymer materials then in inorganic solids. The reason for this special behavior are related on one side to the large polarisabilities of organic conjugated molecules  and to permanent dipoles on part of those of interest , and on the other hand on the high electron-phonon interactions leading to the presence of clearly identified polaronic state in polymers [5, 6, 7, 8].The presence of disorder in most OLED (Organic Light Emitting Diode) materials acts also in synergy with both Coulomb interactions and electron-phonon interactions: a slow carrier in a disordered material interacts with other electrons and dipoles in a much stronger way than a fast one and relaxes the lattice more efficently than a fast one.Instead of applying the transport results established for the semiconductors, the work of our group aims to develop truly molecular model applicable to soft matter. Some of the aspects of this work is illustrated below.
M.N. Bussac, E. Tutis, L. Zuppiroli, "Charge transport modeling in organic light emitting diodes" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP17), 2001, pp 554 - 556, https://doi.org/10.2352/ISSN.2169-4451.2001.17.1.art00026_2