The mechanism of the CuPc/metal/Al multilayer cathode in organic light emitting diodes

Abstract

Organic light emitting diode (OLED) devices were developed using a CuPcmetalAl multilayer structure as cathode, and Li, Ca, and Mg were employed as metals. The typical device structure is composed of a glass substrate/indium tin oxide (ITO)/ N, N′ -diphenyl- N, N′ -(3-methyl phenyl)-1, 1′ -biphenyl-4, 4′ -diamine (TPD)/tris (8-quinolinolato) Al (Alq3) /copper phthalocyanine (CuPc)metalAl. The CuPcmetalAl cathode can improve the performance of OLEDs by decreasing the turn-on voltage and increasing the efficiency of the device. A comparable luminous efficiency can be reached in the device structure ITOTPD Alq3 CuPcLiAl as compared with the LiFAl bilayer cathode one. The mechanism of CuPcmetalAl cathode in OLED devices is discussed in this paper. © 2008 The Electrochemical Society.