Regensburg 2004 – scientific programme

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.35: Poster

Thursday, March 11, 2004, 18:00–21:00, B

Energy Shifts in Copper Phthalocyanine Grown on Hydrogen Passivated Si(111) — •M. Gorgoi, T. U. Kampen, and D. R. T. Zahn — Insitut f"ur Physik, TU Chemnitz, 09107 Chemnitz, Germany

Being a major component in organic light emitting devices and solar cells, copper phthalocyanine (CuPc) owes its increasingly attractive application potential to its optical and electronic properties. In this contribution ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPES) were employed to study the electronic density of states of CuPc layers deposited onto hydrogen passivated Si(111) substrates as a function of film thickness. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) features are found to shift gradually in the same direction with increasing film thickness. HOMO and LUMO shift away from and towards the Fermi level, respectively. Saturation occurs at approximately 10 nm coverage, when the shifts amount to about 0.4 eV. In spite of this shift, the HOMO – LUMO peak to peak difference is found to be constant at (2.95 – 0.25) eV in agreement to previous studies [1]. The 0.4 eV shifts of the HOMO and LUMO are proposed to originate from the growth morphology of CuPc. [1] I.G.Hill, A. Kahn, Z.G. Soos, R.A. Pascal, Jr., Chem. Phys. Lett. 327, 181, (2000)