Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 16: Organic, polymeric, biomolecular films - also with adsorbates
O 16.3: Vortrag
Montag, 22. März 2010, 15:30–15:45, H46
Light effective mass of the valence band hole of rubrene single crystal observed by angle-resolved photoelectron spectroscopy — •Satoshi Kera, Steffen Duhm, Shunsuke Hosoumi, Qian Xin, Nobuo Ueno, Shinichi Machida, Akihiro Funakoshi, Naoki Ogawa, Yasuo Nakayama, and Hisao Ishii — Grad. School of Advanced Integration Science, Chiba University
The mechanism of the carrier transport in organic semiconductor has remained in puzzling at room temperature region, especially. Rubrene (C42H28) single crystal has been recognized to exhibit the highest hole mobility among all organic semiconductors [1]. To comprehend the transport nature as well as to improve the device performance, information on the electronic structure is indispensable. In the present study, we successfully observed the valence electronic structures of rubrene single crystal by angle-resolved ultraviolet photoelectron spectroscopy with laser illumination to avoid sample charging. A clear energy dispersion of the highest occupied molecular orbital band was observed, where the dispersion width is 0.4 eV along the well conjugated direction. Effective mass of holes is estimated to be 0.7 m0. The present results suggest that the carrier conduction mechanism in a rubrene single crystal should be described as band transport of a delocalized light quasiparticle [2].
[1] T. Hasegawa and J. Takeya, Sci. Technol. Adv. Mater. 10, 024314 (2009). [2] S. Machida et al, submitted.