[17p-F202-1~12] 9.5 New functional materials and new phenomena

[17p-F202-9] A new structure of pentacene induced by interaction with a substrate

〇Tetsuroh Shirasawa¹, Susumu Yanagisawa², Shin-nosuke Hatada³, Wolfgang Voegeli⁴, Yoshitada Morikawa³, Toshio Takahashi⁴ (1.AIST, 2.Univ. of the Ryukyus, 3.Osaka Univ., 4.Tokyo Gakugei Univ.)

Keywords:organic semiconductor, surface x-ray diffraction, electronic structure

Pentacene, one of the most studied organic semiconductors, crystallizes in different structures depending on the growth condition. The structure is usually classified into one of the three polymorphs, the so-called single crystal phase, bulk phase, and thin _lm phase. In this letter, we show that epitaxial crystalline pentacene thin films on Bi(0001), which are known to have the lattice parameters of the bulk phase, have a distinct molecular orientation. The calculated band structures show an excellent agreement with the experimental data for the bandwidth [S. Ciuchi et al., Phys. Rev. Lett. 108, 256401 (2012)]. One of the two main intermolecular interactions is almost identical to that of the single crystal phase, while the other one is almost identical to the bulk phase. The results indicate that polymorphs in the same lattice can be formed by a molecular-substrate interaction.