Improved performance and stability of organic light-emitting devices with Al-Cu alloy cathode

Abstract

We have developed a stable green organic electroluminescent (EL) device by using an Al-Cu alloy as a cathode, which has better performance and reliability than the device with an Al cathode. The device with an Al-Cu alloy cathode achieved an EL efficiency of 3.78 cd/A(2.18 lm/W) at 20 mA/cm(2) and the operating voltage was 5.46 V, while device with Al cathode had an EL efficiency of 3.1 cd/A(1.34 lm/W) and 7.3 V at the same drive condition. The Al-Cu device achieved a 20% decay lifetime (t(80)) of 1234 h at an initial brightness of 756 cd/m(2), which is twice the lifetime of conventional device with the state-of-the-art LiF/Al cathode. (C) 2005 American Institute of Physics.