Air-assisted High-performance Field-effect Transistor with Thin Films of Picene

Abstract

A field-effect transistor (FET) with thin films of picene has been fabricated on SiO2 gate dielectric. The FET showed p-channel enhancement-type FET characteristics with the field-effect mobility, mu, of 1.1 cm2 V-1 s-1 and the on-off ratio of >10(5). This excellent device performance was realized under atmospheric conditions. The mu increased with an increase in temperature, and the FET performance was improved by exposure to air or O2 for a long time. This result implies that this device is an air (O2)-assisted FET. The FET characteristics are discussed on the basis of structural topography and the energy diagram of picene thin films.

Accessing Surface Brillouin Zone and Band Structure of Picene Single Crystals

“…In the tight-binding approximation, the effective mass of the hole m h * can be given by m h * = 2 /2tb 2 , while our results gives m h * = 2.24 m 0 (m 0 : the free electron mass). In a broad band model (W > k B T ), the hole mobility µ h can be estimated as µ h ≥ 20 (m 0 /m * ) × (300/T ) [22], so that the lower limit of µ h is 9.0 cm 2 /Vs at 298 K. This value is comparable to the largest µ h (∼5 cm 2 /Vs) of reported picene thin film transistors [7,8], and suggests that the hole mobility in the thin films is dominated by the band transport [7,8,14,23].…”

Electronic structure of pristine and K-doped solid picene: Nonrigid band change and its implication for electron-intramolecular-vibration interaction

“…The details of the procedure are described in a literature. 7 Pristine picene thin films for the measurements at Hiroshima Synchrotron Radiation Center ͑HiSOR͒ were prepared by in situ deposition of picene powder on Au-coated stainless substrates under ultrahigh vacuum. X-ray diffraction of the solid pristine picene films showed that they have the same crystal structure as that of solid picene.…”

“…3. This binding energy of the valence band maximum is nearly half of the band gap, 7 suggesting that solid pristine picene is an intrinsic semiconductor. We also observed no intensity at E F , consistent with semiconducting properties of pristine picene.…”

First-Principles Electronic Structure of Solid Picene

“…A picene molecule consists of five benzene rings joined in an armchair manner with a higher chemical stability than pentacene with a straight arrangement. The solid picene has in fact a much larger band gap (' 3:3 eV) 9) than that of solid pentacene (' 1:8 eV), which is why the material originally attracted attention as an organic semiconductor in e.g. organic FET's.…”

“…organic FET's. 9,10) Picene has been known to crystallize in orthorhombic and monoclinic forms, 11) and Kubozono's group discovered superconductivity in potassium-doped monoclinic crystalline picene. 8) The crystal comprises layers stacked in c direction, where each layer (in ab plane) has picene molecules arranged in a herringbone structure.…”