Abstract: The energy band structure (dispersion relation between energy and wavenumber) is fundamental information essential for elucidating the charge transport properties of semiconductors. For organic semiconductors, the valence band structure, which is responsible for
hole transport, has been measured by energy-dependent and angle-resolved photoelectron spectroscopy since the 1990s. However, the conduction band structure, which is responsible for electron transport, has not yet been reported.
 

We have developed a new technique, angle-resolved low-energy inverse photoelectron spectroscopy [1], and succeeded in measuring the conduction band structure of organic semiconductors for the first time [2]. Based on the experimental results, we propose a new polaron model, "partially-dressed polaron" model. This study evidences the polaron formation in high-mobility organic semiconductors has a significant impact on electronic conduction.

[1] Y. Kashimoto, S. Ideta, H. Sato, H. Orio, K. Kawamura, H. Yoshida,
Rev. Sci. Instrum., 94, 063903 (2023). Selected as Editor’s Pick
[2] H. Sato, S. A. Abd. Rahman, Y. Yamada, H. Ishii, H. Yoshida, Nature
Mat. 21, 910 (2022).