Computational Analysis on Organic Light Emitting Diodes with Varying Energy Level of Hole Injection Layer

초록

We report a numerical study on multilayer Organic Light Emitting Diodes (OLEDs) device which comprises a thin CuPc layer for hole injection layer (HIL). We used S-TAD (2,2′,7,7′- tetrakis-(N,N- diphenylamino)-9,9′-spirobifluoren) for hole transfer layer, S-DPVBi (4,4'-bis (2,2'- diphenylvinyl) -1,1'- spirobiphenyl) for Emission layer and Alq3 (Tris (8- hyroxyquinolinato) aluminium) for the electron transfer layer. We varied the level of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the thin CuPc layer for preparing five OLED devices. The first one is the reference device of which the HIL has 5.3 eV of HOMO level and 3.8eV of LUMO level. The next one is the tri-layer device which doesn’t have HIL. Another is the four layer device which has 4.5eV of LUMO level. Finally, we varied HOMO level of HIL as 5.4 eV and 5.5 eV, these two device also used for our simulation. In this work, we simulated carrier injection, transportation and recombination of these five devices. Thereby we investigated the effect of HIL and demonstrated that the characteristic of these devices has been improved by a thin layer of CuPc between the anode and HTL.