We report our finite element method (FEM) simulation study on the characteristic of the charge transport layer of the multi-layer structure for organic light emitting diodes (OLEDs). The physical model cover all the key physical processes in OLEDs, namely charge injection, transport and recombination, exciton diffusion, transfer and decay for electronic properties. We performed a numerical simulation on a multilayer structure comprising a hole transport layer (HTL), an emission layer (EML), and an electron transport layer (ETL) between both electrodes; anode and cathode. The materials of the HTL is TPD (N, N'-Bis (3- methylphenyl) - N, N'- bis (phenyl) benzidine), and the ETL includes Alq3 (Tris (8- hyroxyquinolinato) aluminium). Here, we investigated the parameters such as recombination rates which influence the efficiency of the charge transport between layers in bilayer OLEDs. We also analyzed a transient response during the turn on period and the carrier transport in accordance with the variation of the injection barrier and applied voltage. In addition, this paper revealed that the effect of the insertion of the EML in bilayer structure.
Oxadiazole derivatives as bipolar host materials for high-performance blue and green phosphorescent organic light-emitting diodes