Four times lifetime improvement of blue phosphorescent organic light-emitting diodes by managing recombination zone

Lifetime of blue phosphorescent organic light-emitting diodes (OLEDs) was improved by suppressing a recombination zone shift using a high triplet energy exciton blocking layer. Host material of the emitting layer was inserted as the exciton blocking layer between a hole transport layer and an emitting layer, and the exciton blocking layer kept the recombination zone near hole transport layer side without significant emission zone change during lifetime test. The suppressed recombination zone shift improved the lifetime of the blue phosphorescent OLED by four times.