Organic light-emitting devices with a mixed layer acting as a hole transport and as an emitting/electron transport layer

The electrical and the optical properties of organic light-emitting devices (OLEDs) with a mixed layer acting as a hole transport layer and as an emitting layer/electron transport layer were investigated. The OLEDs with a mixed layer showed the highest efficiency, and the emitting color of the OLEDs was pure yellow. The enhancement of the luminous efficiency in the OLEDs with a mixed layer was attributed to a decrease in hole mobility.