White Organic Light‐Emitting Diodes Using Exciplex Emission with Multiple Emitting Layers

In this paper, multiple‐exciplexed white organic light‐emitting diodes (WOLEDs) with blue and yellow–green emitting layers (EMLs) to improve charge balance and efficiency roll‐off through exciton confinement are investigated. Several types of WOLEDs are fabricated a number of including exciplex generated by only host materials without fluorescent or phosphorescent dopant. Moreover, various multiple exciplex can control electrical behavior of holes and electrons in whole EML. The performance improvement by the insertion of multi‐EMLs is realized throughout enhancement of exciton confinement and the reduced exciton quenching in EML. Efficiency roll‐off was 40% improved comparing to WOLED without multi‐EMLs and also color rendering index was achieved higher than 70 at 1000 cd m −2 in WOLED with multi‐EMLs.