Deep insight into the electronic structure of organic single crystal: rubrene

Understanding the impacts of weak electronic interaction on the electron delocalization is required to discuss the rich functionalities of organic molecular materials. Moreover, effects of the strong coupling of phonon (collective lattice vibration) and/or local molecular vibration to the electron must be unveiled. Angle-resolved UPS (ARUPS) is known to be a powerful technique to study the electronic structure. The HOMO-band features can offer a wide variety of key information, that is essential to comprehend charge- hopping transport (small-polaron related transport) [1] as well as to coherent band transport in the molecular single crystal [2,3]. However, the experimental study of fine features in the HOMO state has not been progressed till recently due to difficulty in the sample preparation, damages upon irradiation, and so on [4,5]. We present recent findings regarding on the precise measurements of the electronic structure of rubrene (C42H28) single crystals by using synchrotron-light based, high-resolution ARUPS. We describe the characteristic electronic structure of rubrene that 1) the UPS HOMO bands show a clear linear dichroism for bonding and anti-bonding HOMO, 2) a band- unfolding behavior as for intrinsic spectral function of HOMO, and 3) polaron-like quasiparticle effects on the electronic structure. The precise experiments of the 2D momentum scan in the ARUPS would provide a perspective of designing the organic semiconductor devices in non-trivial way.
References[1] S. Kera, H. Yamane. N. Ueno, Prog. Surf. Sci. 84 (2009) 135-154.[2] N. Ueno and S. Kera, Prog. Surf. Sci. 83 (2009) 490- 557.[3] Y. Nakayama, S. Kera, and N. Ueno, J. Mater. Chem. C 8 (2020) 9090-9132.[4] S. Machida, et al. Phys Rev. Lett. 104 (2010) 156401. [5] F. Bussolotti, et al., Nat. Comm. 8 (2017) 173.
Host: Frederik Schiller

Hybrid Seminar: Donostia International Physics Center


Satoshi Kera, Institute for Molecular Science, Okazaki, Japan

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