A Numerical Study on the Charge Transport in TPD/Alq3-based Organic Light Emitting Diodes

초록

We report our numerical study on the effect of inserting the emission layer in bilayer organic light emitting diodes (OLEDs) structure. For comparison, we call a basic 2-layer as device A. Then, we insert the EML between transport layers to make 3-layer devices B and C. In device B, the Lowest Unoccupied Molecualr Orbital (LUMO) level of the EML aligns with the LUMO of the ETL while the Highest Occupied Molecular Orbital (HOMO) level of the EML aligns with the HOMO of the HTL. In Device C, the LUMO level of the EML aligns with the LUMO of the HTL while the HOMO level of the EML aligns with the HOMO of the ETL. If the device structure is charge-blocking device B, the recombination occurs at both edge of the EML as the electric field peaks at these areas. But if the structure is charge-confining device C, electric field is confined at the interface between EML and electron transport layer (ETL).