Low voltage organic light-emitting devices with triphenylphosphine oxide layer

We have developed low voltage driving organic light-emitting devices using triphenylphosphine oxide (Ph3PO) layers. The devices with a Ph3PO layer show high current density at a low voltage. For example, the current density of 20mA∕cm2 is achieved at a low voltage of 2.9V for the device consisted of 4,4′,4″-tris[N-(2-naphthyl)-N-phenyl-amino]-triphenylamine (2-TNATA), 4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl (DPVBi), and Ph3PO layers. Due to the good electron conduction property of Ph3PO, a luminance of 1017cd∕m2 is achieved at a low voltage of 3.0V in a device with a structure of ITO/2-TNATA/DPVBi:rubrene (1%,10nm)∕DPVBi (30nm)∕Ph3PO (60nm)∕LiF∕Al.