Interaction between organic semiconductors and LiF dopant

X-ray photoemission spectroscopy and optical absorption have been used to study the interaction between LiF dopant and various organic semiconductor hosts including N,N-'-diphenyl-N,N-'-bis (3-methylphenyl)-1, 1(')-biphenyl-4, 4(')-diamine (TPD), N,N-'-bis (1-naphthyl)-N,N-'-diphenyl-1, 1(')-biphenyl-4, 4(')-diamine (NPB), tris (8-hydroxyquinolinato) aluminum (Alq3), C-60, and copper phthalacyanine (CuPc). It was found that there is a charge transfer between host and dopant in the Alq3-LiF and C-60-LiF systems, while no such charge transfer was observed for the TPD-LiF, NPB-LiF, and CuPc-LiF systems. The experimental data show that F- anion acts as an n-type donor-donating electron charge to the electron transport molecules. (C) 2004 American Institute Of Physics.