Host: The Japan Society of Vacuum and Surface Science
Energy band structure is fundamental information about the electronic properties. Although the band structure of the highest occupied molecular orbital of organic semiconductors has been measured for three decades, that of the unoccupied molecular orbital has not been observed. In order to measure it, we have developed a new experimental technique called angle-resolved low-energy inverse photoelectron spectroscopy. In this work, we applied this technique to the thin film of prototypical organic semiconductor, pentacene. We successfully observed the band structure. We also observed the bandwidth narrowing which can be interpreted by the formation of the small polaron.
