title: Crystal structure, spin polarization, solid-state electrochemistry, and high n-type carrier mobility of a paramagnetic semiconductor: vanadyl tetrakis(thiadiazole)porphyrazine.
abstract: We report the synthesis, crystal structure, and magnetic, electrochemical, and carrier-transport properties of vanadyl tetrakis(thiadiazole)porphyrazine (abbreviated as VOTTDPz) with S = ½. X-ray crystal analysis reveals two polymorphs, the α and β forms; the former consists of a 1D regular π stacking, while the latter forms a 2D π network. Molecular orbital calculations suggest a V(4+)(d(1)) ground state and a characteristic spin polarization on the whole molecular skeleton. The temperature dependence of the paramagnetic susceptibility of the α form clearly indicates a ferromagnetic interaction with a positive Weiss constant of θ = 2.4 K, which is well-explained by McConnell's type I mechanism. VOTTDPz forms amorphous thin films with a flat and smooth surface, and their cyclic voltammogram curves indicate a one-electron reduction process, which is highly electrochromic, because of a reduction of the porphyrazine π ring. Thin-film field-effect transistors of VOTTDPz with ionic-liquid gate dielectrics exhibit n-type performance, with a high mobility of μ = 2.8 × 10(-2) cm(2) V(-1) s(-1) and an on/off ratio of 10(4), even though the thin films are amorphous.
authors.affiliation: Department of Chemistry & Research Center for Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Miyoshi
authors.forename: Kouji
authors.initials: K
authors.lastname: Takahashi
authors.forename: Takuya
authors.initials: T
authors.lastname: Fujimoto
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Michio M
authors.initials: MM
authors.lastname: Matsushita
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ouchi
authors.forename: Mikael
authors.initials: M
authors.lastname: Kepenekian
authors.forename: Vincent
authors.initials: V
authors.lastname: Robert
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Donzello
authors.forename: Claudio
authors.initials: C
authors.lastname: Ercolani
authors.forename: Kunio
authors.initials: K
authors.lastname: Awaga