[22a-W631-1~12] 12.2 Characterization and Materials Physics

[22a-W631-7] Effect of molecular quadrupole on the energy levels of organic films

〇Hiroyuki Yoshida¹ (1.Chiba Univ.)

Keywords:organic semiconductor,energy level

Energy levels (e.g. ionization energy and electron affinity) of organic films depend on the orientation of constituent molecules. We have carried out ultraviolet photoemission and low-energy inverse photoemission studies demonstrating that the orientation dependence originates from the electrostatic interactions. In this study, we discuss the energy levels of organic films of pentacenequinone, pentacene, perfluoropentacene etc. based on the electrostatic energy calculated for clusters, where the interaction between the ion and neutral molecule is approximated by that of the charge-permanent quadrupole. The calculation qualitatively reproduces the previous experimental results. Further, it is found that the energy levels depend not only on the molecular orientation but also macroscopic shape of the clusters and molecular arrangements in the cluster.