Charge Injection-Assisted Current Efficiency Improvement in Roll-Off Characteristic of OLEDs by Device Modeling

Electrons and hole carrier imbalance causes a drastic roll-off of the current efficiency in organic light-emitting diodes. Charge injection is used to maintain the charge balance between the electrons and the holes. We demonstrated that the roll-off characteristic depends on the injection barrier in the emission layer that governs the charge balance in the emission layer. Furthermore, the improvement in the roll-off characteristic of the current efficiency is described. We also explained how charge balance is achieved by varying the injection barrier in organic light-emitting diodes.