Taishi Takenobu

Abstract A high‐performance ambipolar light‐emitting transistor (LET) that has high hole and electron mobilities and excellent luminescence characteristics is described. By using this device, a conspicuous light‐confined edge emission and current‐density‐dependent spectral evolution are observed. These findings will result in broader utilization of device potential and they provide a promising route for realizing electrically driven organic lasers.

We measured the external electroluminescence quantum efficiency (eta(ext)) in light-emitting field-effect transistors (LETs) made of organic single crystals and found that, in the ambipolar transport region, eta(ext) is not degraded up to several hundreds A/cm(2) current-density range, which is 2 orders of magnitude larger than that achieved in conventional organic light-emitting diodes. The present result indicates the single-crystal organic LET is a promising device structure that is free from

Low-cost green manufacturing of single-walled carbon nanotube films via precisely controlled inkjet printing is demonstrated. This type of transistor exceeds the performance of conventional organic transistors, both in mobility and the on/off ratio. The production of exclusively inkjet-printed SWCNT transistors with printable ionic-liquid gate dielectrics is also shown. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed,

Abstract The first ambipolar light‐emitting transistor of an organic molecular semiconductor single crystal, tetracene, is demonstrated. In the device configuration, electrons and holes injected from separate magnesium and gold electrodes recombined radiatively within the channel. By varying the applied voltages, the position of the recombination/emission zone could be moved to any position along the channel. Because of the changes made to the device structure, including the use of single crysta

We report that the ternary ${\mathrm{MgB}}_{2\ensuremath{-}x}{\mathrm{C}}_{x}$ compounds adopt an isostructural ${\mathrm{AlB}}_{2}$-type hexagonal structure in a relatively small range of nominal carbon concentration, $x<0.1.$ The lattice parameter a decreases almost linearly with increasing carbon content x, while the c parameter remains unchanged, indicating that carbon is exclusively substituted in the boron honeycomb layer without affecting the interlayer interactions. The superconductin

Transparent flexible thin-film transistors (tf-TFTs) are an important focus of research since present silicon-based electronics cannot realize such devices. Here, we demonstrate a single-walled carbon nanotube (SWNT) tf-TFTs based on the solution process using transparent electrodes. SWNT tf-TFTs typically exhibit a mobility of 0.5cm2∕Vs and an on/off current ratio of ∼104. More importantly, these transistors are highly flexible and can be bent to a radius of 7.5mm without a significant loss in

Extremely high current densities are realized in single-crystal ambipolar light-emitting transistors using an electron-injection buffer layer and a current-confinement structure via laser etching. Moreover, a linear increase in the luminance was observed at current densities of up to 1 kA cm(-2) , which is an efficiency-preservation improvement of three orders of magnitude over conventional organic light-emitting diodes (OLEDs) at high current densities.

A new method for controlling the hole density in single-walled carbon nanotube field-effect transistors (SWCNT-FETs) by solution-based chemical doping is presented. The use of organic molecules that adsorb onto SWCNTs from solution is investigated. The transfer characteristics of the SWCNT-FETs exhibit continuous and precise shifts in threshold voltages (see Figure) upon doping with F4TCNQ molecules, even in air.

A new method for investigating light-emitting property in organic devices is demonstrated. We apply the ambipolar light-emitting transistors (LETs) to directly observe the recombination zone, and find a strong link between the transistor performance and the zone size. This finding unambiguously indicates that the light emission comes from the electric-field-induced p-i-n homojunction in ambipolar LETs.

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.

Ink-jet printable thin-film transistors (TFTs) on flexible plastic substrates are an important focus of research because present silicon-based electronics cannot realize such devices. In the present study, we fabricated single-walled carbon nanotube (SWCNT) TFTs on plastic substrates using the ink-jet printing method, and realized high-on/off current ratio (∼104) and flexibility, respectively. The present study therefore represents a major step towards "flexible SWCNT electronics".