Torahiko Ando

Macromolecular electronic device: Field‐effect transistor with a polythiophene thin film

The first solid‐state field‐effect transistor has been fabricated utilizing a film of an organic macromolecule, polythiophene, as a semiconductor. The device characteristics have been optimized by controlling the doping levels of the polymer. The device is a normally off type and the source (drain) current can be modulated by a factor of 102–103 by varying the gate voltage. The carrier mobility and the transconductance have also been determined to be ∼10−5 cm2/V s and 3 nS, respectively, by means of electrical measurements.

Field-effect transistor with polythiophene thin film

Abstract The first actual field-effect transistor (FET) has been fabricated utilizing polythiophene as an active semiconducting material. The device is normally-off type and the source-drain current can be largely increased by a factor of 10 2 –10 3 by applied gate voltages. Other device parameters have been also determined by electric measurements. The stability of the device is quite excellent and it works well even after the heat-treatment in air.

Polythiophene field-effect transistor: Its characteristics and operation mechanism

Abstract A novel field-effect transistor (FET) with an electrochemically-polymerized polythiophene thin film as an active p-type semiconductor has been fabricated for the first time. The FET is a normally-off type and the source current ( I s ) has been enhanced by a factor of more than 10 3 under applied negative gate biases. The conduction channel has been shown to be due to the accumulation of majority positive carriers. It has also been made clear that the electrical conductivity and the thickness of the polythiophene film have a crucial effect on the FET characteristics. The operation mechanism for the FET has been discussed in detail.

Positive Photoreactive Polyimides. II. Preparation and Characterization of Polyimide Precursors Containing α-(2-Nitrophenyl)ethyl Ester Side Chains

Abstract The monomers were derived from pyromellitic dianhydride and α-(2-nitrophenyl)ethanol, which was prepared by selective reduction of 2-nitroacetophenone. Polyimide precursors were synthesized by an interfacial polycondensation technique. Their thermal properties in nitrogen were studied by dynamic thermogravimetry. The photore-arrangement of 2-nitrobenzyl ester having a methyl group at the α-position compared to that of the unsubstituted ester was investigated by infrared spectrophotometry. The polymers obtained in this study gave a high proportion of photorearrangement to show high sensitivity. The exposed areas dissolved in 2% aqueous KOH, forming high resolution patterns because they did not swell during the developing process.

Effects of polymer matrix on electro-optic properties of liquid crystals mixed with polymer

The presence of hysteresis in transmittance-voltage characteristics of liquid crystal mixed with polymer (LCMP) has been the main cause for the residual image of LCMP display devices. This hysteresis is regarded to originate in the interaction between liquid crystal material and matrix polymer. The molecular motion of the matrix polymer of LCMP is varied systematically by changing the monomer and photo-initiator content. The hysteresis of LCMP decreases as the elastic modulus of matrix polymer decreases. It has been found quite effective to lower the elastic modulus of matrix polymer in reducing the hysteresis of LCMP.

LARGE AREA LIQUID CRYSTAL DISPLAY FOR AUTOMOBILE

An instrument panel of a large area liquid crystal display (LCD), including a 50 segment bargraph speedometer, a six digit odo/trip/tacho meter, two gages and several warning indicators, has been developed. The LCD cell evaluated for this instrument panel is operated in a reflective twisted nematic mode and dimensions of the cell are 260 X 110 X 3 mm. The liquid crystal material is capable of operating over a wider temperature range from -30 deg C to 80 deg C and the response time is less than 1 second at -20 deg C without heaters. The LCD instrument panel can display in multicolor by using high performance dichroic polarizers. Finally feasibility of the large area LCD instrument panel is investigated.