Separation in the Roles of Carrier Transport and Light Emission in Light-Emitting Organic Transistors with a Bilayer Configuration.

To develop high-performance organic light-emitting organic field-effect transistors (LE-OFETs), a fundamental problem in organic semiconductors is to compromise light luminescent efficiency for high carrier mobility and vice versa. Therefore, LE-OFETs can avoid this problem by separating the light-emission and carrier-transport functions. Here, a bilayer LE-OFET composed of a tetracene crystal as a carrier transporter (bottom crystal) and a 4-(dicyanomethylene)-2-methyl-6-( p-dimethylaminostyryl)-4 H-pyran (DCM1)-doped tetracene crystal as a light emitter (top crystal) was fabricated.

A new electrode design for ambipolar injection in organic semiconductors.

Organic semiconductors have attracted much attention for low-cost, flexible and human-friendly optoelectronics. However, achieving high electron-injection efficiency is difficult from air-stable electrodes and cannot be equivalent to that of holes. Here, we present a novel concept of electrode composed of a bilayer of tetratetracontane (TTC) and polycrystalline organic semiconductors (pc-OSC) covered by a metal layer.

Electric Properties of Dirac Fermions Captured into 3D Nanoporous Graphene Networks.

Nanoporous graphene- based electric-double-layer transistors (EDLTs) are successfully fabricated. Transport measurements of the EDLTs demonstrate that the ambipolar electronic states of massless Dirac fermions with a high carrier mobility are well preserved in 3D nanoporous graphene along with anomalous nonlinear Hall resistance and exceptional transistor on/off ratio. This study may open a new avenue for device applications of graphene.

Biphenyl end-capped bithiazole co-oligomers for high performance organic thin film field effect transistors.

Two new regiospecific biphenyl end-capped bithiazole co-oligomers, BP2Tz(in) and BP2Tz(out), have been synthesized for application in thin film field effect transistors (TFTs). BP2Tz(in) with a 2,2'-bithiazole central unit exhibits a field effect hole mobility as high as 3.5 cm(2) V(-1) s(-1).

2-Positional pyrene end-capped oligothiophenes for high performance organic field effect transistors.

Three new 2-positional pyrene end-capped oligothiophene co-oligomers, BPynT (n = 1, 2, 3), have been synthesized for application in organic field effect transistors (OFETs). BPy2T showed the highest hole mobility of 3.3 cm(2) V(-1) s(-1) in a single crystal OFET and a good photoluminescence efficiency of 32% in the crystalline state.

Tuning of the ground state in electron doped anthracene.

High quality bulk samples of anthracene (AN) doped with potassium (K) in 1 : 1 and 2 : 1 stoichiometries were successfully prepared by a method involving a room temperature solid-state mechanical diffusion process prior to intercalation reactions during heat treatment, and their physical properties were studied using both magnetic and optical measurements. The transfer of almost one electron from K to AN in K1(AN) was confirmed by SQUID and ESR measurements. A pronounced magnetic hump centered at 150 K associated with antiferromagnetic interactions was observed, which can most likely be interpreted in terms of on-site Coulomb repulsions of the Mott insulating states.

High-sensitivity photodetectors based on multilayer GaTe flakes.

Optoelectronic devices based on layered materials such as graphene have resulted in significant interest due to their unique properties and potential technological applications. The electric and optoelectronic properties of nano GaTe flakes as layered materials are described in this article. The transistor fabricated from multilayer GaTe shows a p-type action with a hole mobility of about 0.

Tunable surface electron spin splitting with electric double-layer transistors based on InN.

Electrically manipulating electron spins based on Rashba spin-orbit coupling (SOC) is a key pathway for applications of spintronics and spin-based quantum computation. Two-dimensional electron systems (2DESs) offer a particularly important SOC platform, where spin polarization can be tuned with an electric field perpendicular to the 2DES. Here, by measuring the tunable circular photogalvanic effect (CPGE), we present a room-temperature electric-field-modulated spin splitting of surface electrons on InN epitaxial thin films that is a good candidate to realize spin injection.

Ambipolar organic single-crystal transistors based on ion gels.

Ambipolar electric double-layer transistors (EDLTs) using organic single crystals and ion-gel electrolytes are successfully created by optimising the fabrication of gel films. The p- and n-type EDLTs enable us to investigate the HOMO-LUMO gap energy of semiconductors, offering a new method with which to measure it.

Tunable spin-orbit interaction in trilayer graphene exemplified in electric-double-layer transistors.

Taking advantage of ultrahigh electric field generated in electric-double-layer transistors (EDLTs), we investigated spin-orbit interaction (SOI) and its modulation in epitaxial trilayer graphene. It was found in magnetotransport that the dephasing length L(φ) and spin relaxation length L(so) of carriers can be effectively modulated with gate bias. As a direct result, SOI-induced weak antilocalization (WAL), together with a crossover from WAL to weak localization (WL), was observed at near-zero magnetic field.

Strain-mediated phase control and electrolyte-gating of electron-doped manganites.

A prototype Mott transistor, the electric double layer transistor with a strained CaMnO(3) thin film, is fabricated. As predicted by the strain phase diagram of electron-doped manganite films, the device with the compressively strained CaMnO(3) exhibits an immense conductivity modulation upon applying a tiny gate voltage of 2 V.

Liquid-gated ambipolar transport in ultrathin films of a topological insulator Bi2Te3.

Using ionic-liquid (IL) gating in electric-double-layer transistors (EDLTs), we investigate field-effect electrical transport properties of ultrathin epitaxial films of a topological insulator (TI), Bi(2)Te(3). Because of their extreme thinness, the Bi(2)Te(3) films show a band gap opening and resulting semiconducting transport properties. Near room temperature, an obvious ambipolar transistor operation with an ON-OFF ratio close to 10(3) was observed in the transfer characteristics of liquid-gated EDLTs and further confirmed by a sign change of the Hall coefficients.

Vibrational properties of noble gas endohedral fullerenes.

Analysis of IR and Raman spectra of Ar@C(60) and Kr@C(60) shows that the incorporation of noble gas atoms causes a blue shift of low energy vibrations, which have radial character, and a red shift of higher energy ones which have a tangential character movement. The mechanism of these phenomena is explained on the basis of ab initio numerical experiments with DFT and MP2 procedures. Methodological discussions are advanced, altogether with a scheme for the estimation of the van der Waals interaction between fullerene and noble gas, based on the frequency shifts.

Electrostatic and electrochemical nature of liquid-gated electric-double-layer transistors based on oxide semiconductors.

The electric-double-layer (EDL) formed at liquid/solid interfaces provides a broad and interdisciplinary attraction in terms of electrochemistry, photochemistry, catalysts, energy storage, and electronics because of the large interfacial capacitance coupling and its ability for high-density charge accumulation. Much effort has recently been devoted to the fundamental understanding and practical applications of such highly charged EDL interfaces. However, the intrinsic nature of the EDL charging, whether it is electrostatics or electrochemistry, and how to distinguish them are far from clear.

Hydrogenation-induced surface polarity recognition and proton memory behavior at protic-ionic-liquid/oxide electric-double-layer interfaces.

The electric-double-layer (EDL) formed at liquid/solid interfaces provides a broad and interdisciplinary attraction in terms of electrochemistry, photochemistry, catalysts, energy storage, and electronics. Especially in recent years, much effort has been devoted to the fundamental understanding and practical applications of transistor configurations with EDLs because of their ability for high-density charge accumulation. However, to exploit additional new functionalities of such an emerging interface is not only of great importance but also a huge challenge.

Quantum chemical study on the configurations of encapsulated metal ions and the molecular vibration modes in endohedral dimetallofullerene La2@C80.

The configuration of La ions of La(2)@C(80) in the [80]fullerene cage was investigated by use of quantum chemical calculations. We found that the D(3)(d)() configuration is the global minimum in total energy, being more stable by 1.9 kcal/mol than the D(2)(h)() configuration, which has been considered to be the most stable.

Separation of N2@C60 and N@C60.

We describe the HPLC separation and identification of N@C60 and N2@C60. These species were observed after eleven sequential HPLC separations. Their retention times are in the same range as those of the other noninteractive endohedral species of C60, such as noble gas endohedral C60.

Crystallographic characterization of Kr@C60 in (0.09Kr@C60/0.91C60). (NiII(OEP)).2C6H6.

A sample of C60 containing ca. 9% Kr@C60 has been used to form crystalline (0.09Kr@C60/0.