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Title: Electronic structure evolution and energy level alignment at C{sub 60}/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine]/MoO{sub x}/indium tin oxide interfaces

The electronic structure evolution and energy level alignment have been investigated at interfaces comprising fullerene (C{sub 60})/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine] (TAPC)/ molybdenum oxide (MoO{sub x})/ indium tin oxide with ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy. With deposition of TAPC upon MoO{sub x}, a dipole of 1.58 eV was formed at the TAPC/MoO{sub x} interface due to electron transfer from TAPC to MoO{sub x}. The highest occupied molecular orbital (HOMO) onset of TAPC was pinned closed to the Fermi level, leading to a p-doped region and thus increasing the carrier concentration at the very interface. The downward band bending and the resulting built-in field in TAPC were favorable for the hole transfer toward the TAPC/MoO{sub x} interface. The rigid downward shift of energy levels of TAPC indicated no significant interface chemistry at the interface. With subsequent deposition of C{sub 60} on TAPC, a dipole of 0.27 eV was observed at the C{sub 60}/TAPC heterojunction due to the electron transfer from TAPC to C{sub 60}. This led to a drop of the HOMO of TAPC near the C{sub 60}/TAPC interface, and hence further enhanced the band bending in TAPC. The band bending behavior was also observed in C{sub 60}, similarly creating a built-in field inmore » C{sub 60} film and improving the electron transfer away from the C{sub 60}/TAPC interface. It can be deduced from the interface analysis that a promising maximum open circuit voltage of 1.5 eV is achievable in C{sub 60}/TAPC-based organic photovoltaic cells.« less
Authors:
 [1] ;  [2] ;  [1] ; ; ;  [3]
  1. Hunan Key Laboratory for Super-microstructure and Ultrafast Process, College of Physics and Electronics, Central South University, Changsha 410083 (China)
  2. (United States)
  3. Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States)
Publication Date:
OSTI Identifier:
22273489
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CONCENTRATION RATIO; DIPOLES; ELECTRON TRANSFER; ELECTRONIC STRUCTURE; EMISSION SPECTROSCOPY; FERMI LEVEL; FULLERENES; HETEROJUNCTIONS; HOLES; INDIUM COMPOUNDS; INTERFACES; MOLECULAR ORBITAL METHOD; MOLYBDENUM OXIDES; PHOTOEMISSION; PHOTOVOLTAIC CELLS; THIN FILMS; TIN OXIDES; ULTRAVIOLET RADIATION