Air-Stable Thin Films with High and Anisotropic Electrical Conductivities Composed of a Carbon-Centered Neutral π-Radical

Hiroshi Ito; Tsuyoshi Murata; Takahiro Miyata; Miwa Morita; Ryotaro Tsuji; Yasushi Morita

doi:10.1021/acsomega.9b02700

Air-Stable Thin Films with High and Anisotropic Electrical Conductivities Composed of a Carbon-Centered Neutral π-Radical

ACS Omega. 2019 Oct 9;4(17):17569-17575. doi: 10.1021/acsomega.9b02700. eCollection 2019 Oct 22.

Authors

Hiroshi Ito¹, Tsuyoshi Murata¹, Takahiro Miyata¹, Miwa Morita¹, Ryotaro Tsuji², Yasushi Morita¹

Affiliations

¹ Department of Applied Chemistry, Faculty of Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392, Japan.
² Material Solutions New Research Engine, KANEKA Corporation, Suita, Osaka 565-0871, Japan.

Abstract

Air-stable thin films (50-720 nm thickness) composed of a carbon-centered neutral π-radical with high and anisotropic electrical conductivities were fabricated by vapor deposition of 4,8,12-trioxotriangulene (TOT). The thin films were air-stable over 15 months and were the aggregate of TOT microcrystals, in which a one-dimensional π-stacking column was formed through the strong singly occupied molecular orbital (SOMO)-SOMO interaction with two-electron-multicenter bond among the spin-delocalized π-planes. The orientations of the one-dimensional column of TOT were changed depending on the deposition rate and substrates, where face-on-oriented thin films were epitaxially grown on the graphite 0001 surface, and edge-on-oriented thin films were grown on glass, SiO₂, and indium tin oxide substrates under a high-deposition rate condition. The films showed high electrical conductivities of 2.5 × 10^-2 and 5.9 × 10^-5 S cm^-1 along and perpendicular to the π-stacking column, respectively, for an edge-on oriented thin film.