Combined photoemission/in vacuo transport study of the indium tin oxide/copper phthalocyanine/N,N′-diphenyl-N,N′-bis(l-naphthyl)-1,1′biphenyl-4,4"diamine molecular organic semiconductor system

Ultraviolet photoemission spectroscopy (UPS) was used to study the indium tin oxide/copper phthalocyanine (CuPc) and CuPc/N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'biphenyl-1-4,4 " diamine interfaces, which are commonly used as an anode/hole injection layer/hole transport layer combination in organic light emitting devices. In order to assess the validity of the transport barriers measured using UPS, in vacuo I-V measurements have been performed on simple devices grown and measured in the same system as the samples studied using UPS. I-V characteristics were modeled using numerical simulations. The parameters used in the simulated curves which best fit the measured I-V characteristics agree quantitatively with the UPS measured barriers. (C) 1999 American Institute of Physics. [S0021-8979(99)04716-7].