Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 29: Organic Photovoltaics II: mainly Phtalocyanine

HL 29.1: Talk

Monday, March 14, 2011, 17:45–18:00, FOE Anorg

Band gap states of copper phthalocyanine thin films induced by nitrogen exposure — •Tomoki Sueyoshi^1,2, Haruya Kakuta¹, Masaki Ono¹, Kazuyuki Sakamoto¹, Satoshi Kera¹, and Nobuo Ueno¹ — ¹Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan — ²Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany and JARA-Fundamentals of Future Information Technology

Extensive experimental and theoretical investigations have demonstrated the strong correlation between electronic and structural properties of organic layers. Although understanding of this correlation is very crucial, the question whether the intrinsic or externally induced disorder in the molecular packing structure influences their electronic properties remains obscure.

Here we investigated impact of 1-atm N2 gas exposure on the electronic states of copper phthalocyanine thin films using ultrahigh-sensitivity ultraviolet photoelectron spectroscopy. The highest occupied molecular orbital band of the film showed a drastic reversible change in the bandwidth and band shape as well as in the energy position upon repeated cycles of N2 exposure and subsequent annealing. Furthermore, two types of gap-state densities with Gaussian and exponential distributions appeared after the exposure and disappeared due to the annealing. These changes are ascribed to a weak disorder in the molecular packing structure induced by N2 diffusion into the film.