한국정보디스플레이학회:학술대회논문집

The Korean Infomation Display Society (한국정보디스플레이학회)
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Energy Level Alignment between Hole Injecting HAT-CN and Metals and Organics: UPS and ab-initio Calculations

  • Kang, H. (Dept. of Physics, Kyung Hee University) ;
  • Kim, J.H. (Dept. of Physics, Kyung Hee University) ;
  • Kim, J.K. (Dept. of Physics, Kyung Hee University) ;
  • Kwon, Y.K. (Dept. of Physics, Kyung Hee University) ;
  • Kim, J.W. (Korea Research Institute of Standards and Science) ;
  • Park, Y. (Dept. of Physics, Kyung Hee University)
  • Published : 2009.10.12
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Abstract

We have determined the electronic energy level alignment at the interface between 4,4'-bis-N-phenyl-1-naphthylamino biphenyl (NPB) and 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT-CN) using ultraviolet photoelectron spectroscopy (UPS). The highest occupied molecular orbital (HOMO) of 20 nm thick HAT-CN film was located at 3.8 eV below the Fermi level. Thus the lowest unoccupied molecular orbital (LUMO) is very close to the Fermi level. The HOMO position of NPB was only about 0.3 eV below Fermi level at NPB/HAT-CN interface. This enables an easy excitation of electrons from the NPB HOMO to the HAT-CN LUMO, creating electron-hole pairs across this organic-organic interface. We also study the interaction of HAT-CN with a few metallic surfaces including Ca, Cu, and ITO using UPS and ab-inito electronic structure calculation techniques.

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