Published papers

We have successfully demonstrated a bezel-less scalable display system by arraying bezel-less PMOLED modules. Each has a lifetime of40,000 hours life, 250-firn encapsulation width, l-mm pixel pitch and a flexible substrate. They were realized by SiN/SiN edge encapsulation and the adoption of a slide bending structure.

The crystal structure and electrical conductivities (including the effect of pressure) of [(CH3)4N][Pt(dmit)2] 2 (dmit = 4,5-dimercapto-1,3-dithiole-2-thione) have been studied. The Pt(dmit)2 anions form dimeric structures arranged as one-dimensional stacks along the [110] and [110] directions. A simple band-energy calculation indicates that the conduction band is formed by the HOMO band of Pt(dmit)2 owing to the strong dimeric nature of the molecular stacks.

β-[(CH3)4N][Pd(dmit)2]2 is isomorphic to [(CH3)4N][Ni(dmit)2]2, which is the first pure π acceptor molecular conductor exhibiting a superconducting transition. The crystal structure at low temperature, pressure dependence of the resistivity and the magnetic susceptibility of β-[(CH3)4N][Pd(dmit)2]2 were examined. The general features of the phase diagram of β-[(CH3)4N][Pd(dmit)2]2 resemble those of the organic superconductors. At ambient pressure, the resistivity increases gradually with lowering temperature. A superconducting transition was observed at 6-9 kbar. The highest Tc was 6.5 K. Between 5 and 6.3 kbar, a characteristic rapid resistivity decrease was observed at the small temperature range above the offset temperature of the superconducting transition. Although the resistivity is not zero, this temperature region can be regarded as a "pre-superconducting region, "Above 9 kbar the metallic state is stabilized down to low temperature. Above 5 kbar, most of the crystals exhibited resistivity anomalies around 60 K, which may be ascribed to the metalinsulator transition of the domains with α-type structure (α-[(CH4)4N][Pd(dmit)2]2), which became mixed in with the crystals of β-[(CH3)4N][Pd(dmit)2]2. The resistivity data of the highly conducting state were very noisy in the pressure range where the superconducting transition could be observed.

The electrical resistivities of organic metals with κ-type molecular arrangements were examined. Superconducting transition temperature (Tc) of alloy system κ-[(ET)1-x(STF)x]2 Cu[N(CN)2]Br (ET=BEDT-TTF, STF=BEDT-DSeDTF) is rapidly depressed with increase of the doping amount of the asymmetric π-donor STF. Tc becomes lower than 1.6 K at x>0.25 but the system retains metallic state at least up to x=0.6. The characteristic resistivity maximum is smeared with increasing x. The metal-insulator transition of κ-ET2Au(CN)2 at 70 K is suppressed by applying "soft pressure" of about 550 bar. The electrical properties and the crystal stuctures of κ-MT2Cu[N (CN)2]X (MT=BMDT-TTF, XCl, Br) were also examined. The crystal of κ-MT2Cu[N(CN)2]X belongs to monoclinic system with space group Cc. The structure of anion sheet closely resembles that of κ-MT2Cu[N(CN)2]X. The electrical resistivity decreases monotonously down to 2 K. © 1993.

Thin-film electronic devices can be integrated with skin for health monitoring and/or for interfacing with machines. Minimal invasiveness is highly desirable when applying wearable electronics directly onto human skin. However, manufacturing such on-skin electronics on planar substrates results in limited gas permeability. Therefore, it is necessary to systematically investigate their long-term physiological and psychological effects. As a demonstration of substrate-free electronics, here we show the successful fabrication of inflammation-free, highly gas-permeable, ultrathin, lightweight and stretchable sensors that can be directly laminated onto human skin for long periods of time, realized with a conductive nanomesh structure. A one-week skin patch test revealed that the risk of inflammation caused by on-skin sensors can be significantly suppressed by using the nanomesh sensors. Furthermore, a wireless system that can detect touch, temperature and pressure is successfully demonstrated using a nanomesh with excellent mechanical durability. In addition, electromyogram recordings were successfully taken with minimal discomfort to the user.

Electrical resistivity of (MeBrDCNQI)2Cu1-xLix shows that the metal-insulator transition of (MeBrDCNQI)2Cu at 155 K is rapidly suppressed with increasing x. The mixed-cation system with x=0.2-0.5 retains a metallic state down to 4 K. The metal instability of DCNQICu is discussed in the light of the mixed-valency of Cu. © 1991.