Electronic properties of interfaces between different sexithiophenes and gold

We present a photoemission study of the interface between sexithiophene and polycrystalline gold. Two different sexithiophenes have been investigated—α‐6T and a derivative of α‐6T(ββ′-DH6T) with additionally attached alkane chains at thiophene rings, which increases its solubility and allows application in solution-based processes. We find an interface dipole of 1.2 eV and we observe chemical interactions for both sexithiophenes. Special attention has been paid to the possible influence of the chemical modification on the electronic properties of the material itself and its influence on the interface properties with gold. In addition, we discuss the differences in the electronic structure of vacuum-sublimated and spin-coated films of ββ′‐DH6T. We find indications for better ordered films applying the solution-based process and the spin-coating procedure leads to oxidation of the organic film.

[1]  D. Briggs,et al.  High resolution XPS of organic polymers , 1992 .

[2]  E. Keim,et al.  High-temperature interaction of nitrogen with thin iron films: Thermal desorption kinetics studies combined with microstructure analysis of Fe-N films , 2003 .

[3]  E. Umbach,et al.  Superstructure formation of large organic adsorbates on a metal surface: A systematic approach using oligothiophenes on Ag(111) , 1998 .

[4]  T. Ohta,et al.  Film growth and X-ray induced chemical reactions of thiophene adsorbed on Au(1 1 1) , 2003 .

[5]  E. Umbach,et al.  A combined photoelectron spectroscopy and capacity–voltage investigation of the aluminum/oligothiophene interface , 1999 .

[6]  Mixing of interface dipole and band bending at organic/metal interfaces in the case of exponentially distributed transport states , 2003 .

[7]  S. Semancik,et al.  Doping effects and reversibility studies on gas-exposed α-sexithiophene thin films , 1998 .

[8]  J. G. Snijders,et al.  Density-functional study of the evolution of the electronic structure of oligomers of thiophene: Towards a model Hamiltonian , 2001 .

[9]  K. Seki,et al.  ENERGY LEVEL ALIGNMENT AND INTERFACIAL ELECTRONIC STRUCTURES AT ORGANIC/METAL AND ORGANIC/ORGANIC INTERFACES , 1999 .

[10]  Antoine Kahn,et al.  Molecular level alignment at organic semiconductor-metal interfaces , 1998 .

[11]  M. Knupfer,et al.  Electronic properties of interfaces between model organic semiconductors and metals , 2004 .

[12]  Yongli Gao,et al.  Cs doping and energy level shift in CuPc , 2003 .

[13]  G. Koller,et al.  High resolution XPS of bithiophene on clean and S modified Ni(110) , 1996 .

[14]  C. Dimitrakopoulos,et al.  Organic Thin Film Transistors for Large Area Electronics , 2002 .

[15]  E. Umbach,et al.  Orientation and bonding of thiophene and 2,2′-bithiophene on Ag(111): a combined near edge extended X-ray absorption fine structure and Xα scattered-wave study , 2000 .

[16]  G. Koller,et al.  Molecular architecture through substrate patterning: bithiophene on clean and sulphur patterned Ni(110) , 1999 .

[17]  B. Servet,et al.  Molecular engineering of organic semiconductors: design of self-assembly properties in conjugated thiophene oligomers , 1993 .

[18]  M. Knupfer,et al.  Full characterization of the interface between the organic semiconductor copper phthalocyanine and gold , 2002 .

[19]  C. Ziegler,et al.  Interaction of Na with sexithiophene thin films , 1998 .

[20]  W. A. Dench,et al.  Quantitative electron spectroscopy of surfaces: A standard data base for electron inelastic mean free paths in solids , 1979 .

[21]  Dago M. de Leeuw,et al.  Field-effect transistors made from solution-processed organic semiconductors , 1997 .

[22]  W. R. Salaneck,et al.  Electroluminescence in conjugated polymers , 1999, Nature.

[23]  Vincenzo Spagnolo,et al.  Simultaneous measurement of the electronic and lattice temperatures in GaAs/Al0.45Ga0.55As quantum-cascade lasers: Influence on the optical performance , 2004 .

[24]  W. R. Salaneck,et al.  Coulomb interactions in rubidium-doped tetracyanoethylene: A model system for organometallic magnets , 2004 .

[25]  M. Knupfer,et al.  Energy level alignment at organic/metal interfaces: Dipole and ionization potential , 2002 .

[26]  G. Horowitz,et al.  Growth and Characterization of Sexithiophene Single Crystals , 1995 .

[27]  Stephen R. Forrest,et al.  Efficient bulk heterojunction photovoltaic cells using small-molecular-weight organic thin films , 2003, Nature.

[28]  F. Krebs,et al.  Conformation, Molecular Packing, and Field Effect Mobility of Regioregular β,β‘-Dihexylsexithiophene , 2004 .

[29]  William R. Salaneck,et al.  Hybrid interfaces of conjugate polymers: Band edge alignment studied by ultraviolet photoelectron spectroscopy , 2004 .

[30]  R. Zamboni,et al.  In-situ characterisation of the oxygen induced changes in a UHV grown organic light-emitting diode , 1999 .

[31]  A. Kahn,et al.  Lack of thermodynamic equilibrium in conjugated organic molecular thin films , 2003 .

[32]  E. Umbach,et al.  The influence of oxygen and air on the characteristics of organic light-emitting devices studied by in vacuo measurements , 2000 .

[33]  J. Rowe,et al.  Influence of substrate temperature on epitaxial copper phthalocyanines studied by photoemission spectroscopy , 2004 .

[34]  Gilles Horowitz,et al.  The oligothiophene‐based field‐effect transistor: How it works and how to improve it , 1990 .

[35]  M. Knupfer,et al.  Electronic structure of the organic semiconductor copper phthalocyanine and K-CuPc studied using photoemission spectroscopy , 2002 .

[36]  Howard E. Katz,et al.  Organic molecular solids as thin film transistor semiconductors , 1997 .

[37]  G. Yoshikawa,et al.  One-dimensional ordered structure of α-sexithienyl on Cu(110) , 2004, cond-mat/0403648.

[38]  U. Nagashima,et al.  Ultraviolet photoemission study of oligothiophenes: π-band evolution and geometries , 1990 .