Band dispersion measurements of rubrene single crystals by ARUPS and comparison with theoretical calculations

Abstract

While technological advances have been made in organic devices, the details of charge transport mechanisms in organic semiconductors remain unexplored. In this study, in order to measure the band structure of rubrene single crystals with unprecedented accuracy, we used high quality single crystals and performed comprehensive measurements of band dispersion by angle-resolved ultraviolet photoemission spectroscopy (ARUPS). The band dispersion was observed not only in the Γ-Y direction, which had been identified in previous studies, but also in the Γ-X direction. It was also demonstrated that the Γ point does not determine the lowest gap energy in the Γ-X direction.