Gallium Doping Effects for Improving Switching Performance of p-Type Copper(I) Oxide Thin-Film Transistors.

Copper(I) oxide (Cu2O), which is obtained from copper(II) oxide (CuO) through a reduction process, is a p-type oxide material with a band gap of 2.1-2.4 eV. However, the switching performance of typical Cu2O thin-film transistors (TFTs) is poor because the reduction process increases the concentration of oxygen vacancies (VO), which interfere with the conduction of hole carriers. Ga with high oxygen affinity was doped in Cu2O thin films to decrease VO during the reduction process. As a result, the VO concentration of 1.56 at % for Ga-doped Cu2O (Ga:Cu2O) thin films decreased from 20.2 to 7.5% compared to pristine Cu2O thin films. Accordingly, the subthreshold swing or S-factor, on/off-current ratio (Ion/off), saturation mobility (µsat), and threshold voltage (Vth) of Ga:Cu2O TFTs were improved compared to pristine Cu2O TFTs with values of 7.72 from 12.50 V/dec, 1.22 × 104 from 2.74 × 102, 0.74 from 0.46 cm2/Vs, and -4.56 from -8.06 V, respectively. These results indicate that Ga plays an important role in improving the switching performance of p-type Cu2O TFT.

Simultaneous emission of orthogonal handedness in circular polarization from a single luminophore.

The direct emission of circularly polarized (CP) light improves the efficiency of an organic light-emitting diode and characterizes the secondary structure of proteins. In most cases, CP light is generated from a luminescent layer containing chiral characteristics, thereby generating only one kind of CP light in an entire device. Here, we propose direct CP light emissions using a twisted achiral conjugate polymer without any chiral dopant as an emitting layer (EML). The twisted structure is induced in the mesogenic conjugate polymer due to its elasticity by applying different alignment directions to its upper and lower interfaces. Furthermore, we demonstrate the simultaneous emission of orthogonal CP light in a single luminescent device by patterning different alignment directions on the surfaces of the EML. The light source with multipolarization including the orthogonal CP states is applicable to many applications in biosensors and optical devices.

Numerical simulation of the displayed image on the entire screen of autostereoscopic displays.

A three-dimensional simulation model calculating the optical intensity distribution for the entire screen of an autostereoscopic display at a given eye position was developed in this study. A parallax barrier array was used for the optical model and reverse ray tracing of light from the observer's eye to the subpixels through the slits of the barrier was performed based on reverse geometrical optics. By investigating the optical behavior of the displayed image for the nine-view design condition for various viewing distances, we found the inhomogeneous crosstalk from the unwanted views and predicted segmented images which were comprised of multiple images from different views on the entire display screen. From the results, our simulation model shows good potentiality for predicting the displayed image on the entire display screen of autostereoscopic displays for various positions of the observer's eye with sufficient calculation speed.

Numerical simulation of the optical characteristics of autostereoscopic displays that have an aspherical lens array with a slanted angle.

We developed a 3D simulation model describing the optical phenomena on a slanted lenticular surface with aspherical lenses for autostereoscopic displays and analyzed the optical behavior of the multiview autostereoscopic display under actual design conditions by using a 3D simulation model. Optical characteristics, such as 3D crosstalk and 3D luminance differences, are obtained from the simulation of the light distribution for the multiview autostereoscopic displays with slated angles of 0.0°, 9.46°, 12.59°, and 14.04°. By investigating the effect of the conic constant of an aspherical lens surface on the 3D crosstalk and the 3D luminance differences for given several design conditions, we find the optimal values of the conic constant for slanted angles of 0.0° and 9.46° in order to minimize the 3D crosstalk and the 3D luminance difference. From these results, we think that our simulation model is very useful for designing the lens array to optimize the optical characteristics of autostereoscopic displays.

Three-dimensional modeling of light rays on the surface of a slanted lenticular array for autostereoscopic displays.

In this paper, we developed an optical model describing the behavior of light at the surface of a slanted lenticular array for autostereoscopic displays in three dimensions and simulated the optical characteristics of autostereoscopic displays using the Monte Carlo method under actual design conditions. The behavior of light is analyzed by light rays for selected inclination and azimuthal angles; numerical aberrations and conditions of total internal reflection for the lenticular array were found. The intensity and the three-dimensional crosstalk distributions calculated from our model coincide very well with those from conventional design software, and our model shows highly enhanced calculation speed that is 67 times faster than that of the conventional software. From the results, we think that the optical model is very useful for predicting the optical characteristics of autostereoscopic displays with enhanced calculation speed.