60‐2: Observation of subtle interfacial mixing in solution‐processed OLEDs

We evaluated two polymer hole transport materials (HTM). The difference in the interface‐mixing between the hole transport layer (HTL) and the emitting layer (EML) is shown by the visual method, and it is found that this is the main source of the difference in their lifetime. This will help us to quickly select solution‐processed hole transport materials.