Mitsunaga Saito

Investigation of the organic solar cell characteristics for indoor LED light applications

We report an experimental study on the current–voltage characteristics of organic solar cells (OSCs) under indoor light illumination. A daylight color light-emitting diode (LED) was used as the indoor light source. We investigated the short circuit current density, open circuit voltage, and fill factor of the OSC under LED irradiation and compared them with those for a crystal silicon solar cell (c-Si-SC), which occupy a large part of the solar cell market. We found that compared with the c-Si-SC, the OSC had higher power conversion efficiency (PCE). We also derived the maximum feasible PCE of an OSC for indoor applications and calculated that a PCE value of 21.3% could be obtained under daylight color LED illumination at approximately 200 lx. From the results of the calculation, it became apparent that the open circuit voltage plays an important role in achieving a high PCE from OSCs, indicating they are promising as electrical energy harvesting module for indoor applications.

Influence of channel area scaling on Weibull distribution of TDDB for poly-Si channel FET

Introduction Three-dimensional (3D) integration technology has attracted much attention since it gives rise to the higher packing density, shorter interconnection, lower power consumption and heterogeneous device integration[1]. Recently, 3D-FPGA using TFT configuration SRAM over bulk CMOS logic was proposed[2]. Furthermore, it has been reported that the mobility and ON/OFF current of TFT are dramatically improved when the channel area reduces comparable to the grain size[3]. Therefore, the scaled poly-Si channel transistor in combination with high-performance CMOS device is a promising technology to overcome the conventional CMOS scaling limitation. However, long-term reliability, especially the statistical distribution of reliability, of poly-Si channel FET with small area has not been clarified yet. In this paper, by focusing on the statistical distribution of TDDB for the gate oxide grown on poly-Si with large and small channel area comparing to that on the conventional Si(100) surface, we discuss the guideline in the reliability of gate oxide on poly-Si channel.

Color printer using monocomponent nonmagnetic development system

The development of a compact, high image quality, and maintenance-free electrophotographic color printer suitable for personal computers, EWS, and so on has been demanded. Another important demand is for the development of an electrophotographic printer for which less replacement and less disposal of material is necessary. With this in mind, the authors have been developing a contact type mono-component nonmagnetic development system utilizing a soft and conductive development roller, and a simultaneous development and cleaning process in order to realize a still simpler printing process. In this process, the residual toner remaining on the photoreceptor at the transfer process is cleaned simultaneously by the same development unit, while the latent image is developed by the same unit. Miniaturization of the printer system has been realized and the disposal of the waste toner has become unnecessary, since there is no cleaning unit. The authors have also developed a color toner suitable for a contact type mono-component nonmagnetic development system and have applied it to a four- drum-tandem type color printer. This paper describes the principle of the simultaneous development and cleaning process and the development characteristics of the four-drum- tandem color printer utilizing the development system.