Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Organic photovoltaics and electronics - mostly properties of the absorber (with DS)

HL 19.1: Talk

Monday, March 16, 2015, 17:00–17:15, EW 202

Structural and electronic properties of planar organic heterojunction interfaces and their impact on diode characteristics — •A. Opitz¹, A. Wilke¹, N. Koch^1,2, U. Hörmann³, W. Brütting³, R. Hansson⁴, and E. Moons⁴ — ¹Humboldt-Universität zu Berlin, Germany — ²Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany — ³University of Augsburg, Germany — ⁴Karlstad University, Sweden

The structural and electronic properties of organic heterojunction interfaces are of paramount importance. Here two prototypical interfaces are discussed: diindenoperylene (DIP) combined with fullerene (C60) and copper-phthalocyanine combined with its perfluorinated analog. Angle dependent near edge X-ray absorption fine structure measurements were performed to determine the molecular orientation and compared to measurements of the frontier level alignment by ultraviolet photoelectron spectroscopy.

The orientation of the rod-like DIP molecules is unaffected upon deposition of spherical C60 molecules on top and vacuum level alignment appears. In contrast, cofacial lying interface layers with π-orbital stacking of the two phthalocyanines is observed together with energy level bending. These results will be related to the solar cell performance [1,2]. The combined experimental approach results in a comprehensive model of the investigated interface. The presence of a π-orbital stacking is also of interest for ground-state charge transfer.

[1] J. Wagner et al., Adv. Funct. Mater. 20 (2010) 4295.

[2] A. Opitz et al., Org. Electron. 10 (2009) 1259.