| 초록 |
Exciplex is an excited state charge transfer complex formed between donor and acceptor molecules. Formation of exciplex in organic light emitting diodes (OLEDs) has been considered as an obstacle to increase the efficiency of OLEDs. However, high efficiency phosphorescent OLEDs was reported using an exciplex forming co-host recently. Unfortunately the effect of formation of exciplex in co-host systems on the performance of OLEDs has not been extensively studied yet. We studied the effect of the formation of exciplex in co-hosts on the performance of OLEDs. 3 exciplex forming co-hosts and 2 non-exciplex forming co-hosts were selected for the purpose and used to fabricate OLEDs. OLEDs with the exciplex forming co-hosts showed lower operating voltages than the OLEDs with the hosts not forming exciplex. In case exciplex does not form, there is injection barrier when electrons and holes are injected into emission layer. whereas, in case exciplex forms, there is no injection barrier. |
