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Asuka YAGI Michinori HONMA Ryota ITO Toshiaki NOSE
In recent years, demand for smart windows with dimming and other functions has been increasing, e.g., polymer dispersed liquid crystals. Liquid crystal (LC) gels also have the potential for smart glass applications owing to their light-scattering properties. In this study, LC gels were prepared by mixing nematic LC (E7) with poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) as a gelator. The LC gel formed a dense PFO network as the concentration increased. The PFO network structure changed in response to the change in the cooling rate. High contrast ratio of light scattering was obtained for the LC gel device that was fabricated via the 2-wt%-doping of PFO and natural cooling. Furthermore, the PFO concentration and cooling rate were found to affect the response time of the LC gel device.
Eiji ITOH Taisuke SEKINO Masato KATO
We have developed multilayered polymer-based inverted organic light emitting diodes (iOLED) using transfer-printing and push-coating techniques. We obtained the higher efficiency and lower operation voltage with push-coated blue light emitting polymer and hole transporting polymer than the devices with spin-coated film. The β-phase obtained for blue emitting layer is attributable to the improved performance of relatively efficient bule and white iOLEDs with an external quantum efficiency (EQE) of above 2%.
Hirotake KAJII Masato ISE Hitoshi TANAKA Takahiro OHTOMO Yutaka OHMORI
The effects of the gate dielectrics on ambipolar transport in top-gate-type polymer light-emitting transistors with single-layer and bilayer gate dielectrics are investigated. Hole field-effect mobility is dependent on the dielectric constant of the gate dielectric onto the active layer. Hole transport of devices is affected by the dipolar disorder in the first gate dielectric layer on the active layer. Electron threshold voltage tends to decrease with increasing the total stacked gate capacitance.
Hirotake KAJII Toshinari KOJIMA Yutaka OHMORI
High luminance and high speed response with the cut-off frequency of more than 50 MHz in multilayer polyfluorene-based light-emitting diodes with an interlayer were achieved. We realized multilayer polyfluorene-based light-emitting diodes for frequency response up to 100 MHz.