TY - JOUR
T1 - Observation of filled states at the Fermi-level in alkali-metal intercalated organic films
T2 - Dependence on substrate work function
AU - Koch, N.
AU - Jäckel, F.
AU - Ghijsen, J.
AU - Rojas, M. C.
AU - Grioni, M.
AU - Rabe, J. P.
AU - Johnson, R. L.
AU - Kahn, A.
AU - Pireaux, J. J.
N1 - Funding Information:
Work at HASYLAB was supported by the IHP-Contract HPRI-CT-1999-00040 of the European Commission. The work of AK was supported by the NSF (DMR-00408589) and by the New Jersey Center for Organic Optoelectronics. We acknowledge financial support of the Interuniversity Research Projects (PAI/IUA) on “Quantum Size Effects in Nanostructured Materials” sponsored by the Belgian Prime Minister's Office (Federal Services for Scientific, Technical and Cultural Affairs). R.L.J. acknowledges financial support from the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF) Project No. 05 KS1GUC/3. J. G. acknowledges support by the NFSR (Belgium). Partial support by the EU-RTD program MAC-MES and the Sonderforschungsbereich 448 (DFG) is acknowledged.
PY - 2005/6
Y1 - 2005/6
N2 - We present ultraviolet photoelectron spectroscopy studies on alkali metal-intercalated thin films of electroluminescent p-sexiphenyl (6P) and the organic hole transporting material N,N′-bis-(1-naphthyl)-N,N′- diphenyl1-1,1-biphenyl1-4,4′-diamine (α-NPD). The formation of new occupied electronic states in the otherwise empty energy gap of 6P and α-NPD is observed, accompanied by a significant shift of the Fermi-level. Depending on the work function φ of the substrate used for the organic thin films, we observe two different scenarios at low intercalation levels: the new electronic states are observed at (and even above) EF for high φ substrates, whereas they are observed below EF for low φ substrates. At high intercalation levels, all the states are observed below EF. The observation of states at and above EF is attributed to a lack of thermodynamic equilibrium across the organic thin film.
AB - We present ultraviolet photoelectron spectroscopy studies on alkali metal-intercalated thin films of electroluminescent p-sexiphenyl (6P) and the organic hole transporting material N,N′-bis-(1-naphthyl)-N,N′- diphenyl1-1,1-biphenyl1-4,4′-diamine (α-NPD). The formation of new occupied electronic states in the otherwise empty energy gap of 6P and α-NPD is observed, accompanied by a significant shift of the Fermi-level. Depending on the work function φ of the substrate used for the organic thin films, we observe two different scenarios at low intercalation levels: the new electronic states are observed at (and even above) EF for high φ substrates, whereas they are observed below EF for low φ substrates. At high intercalation levels, all the states are observed below EF. The observation of states at and above EF is attributed to a lack of thermodynamic equilibrium across the organic thin film.
KW - Alkali metals
KW - Organic materials
KW - Photoelectron spectroscopy
KW - Thin films
UR - http://www.scopus.com/inward/record.url?scp=17444386727&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=17444386727&partnerID=8YFLogxK
U2 - 10.1016/j.elspec.2005.01.016
DO - 10.1016/j.elspec.2005.01.016
M3 - Article
AN - SCOPUS:17444386727
SN - 0368-2048
VL - 144-147
SP - 495
EP - 498
JO - Journal of Electron Spectroscopy and Related Phenomena
JF - Journal of Electron Spectroscopy and Related Phenomena
ER -