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NHK Laboratories Note
NHK Laboratories Note No.514
Highly efficient, deep-blue phosphorescent organic light emitting diodes with a double-emitting layer structure

H. Fukagawa, K. Watanabe*1, T. Tsuzuki, S. Tokito
*1:Tokyo University of Science
Applied Physics Letters Vol.93, No.13, 133312, p.3 (2008)

We have demonstrated a highly efficient, deep-blue organic light-emitting diode (OLED) using a host material with a high triplet energy. The OLED device that we have prepared utilizes a phosphorescent guest material, iridium(III)bis(4',6',-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate, exhibits a peak quantum efficiency of about 15.7%. We employed a double-emitting layer (DEL) structure that distributes the carrier recombination region within the device. In this DEL structure, the emission mechanism is such that the energy transfers from the host material in one emitting layer, and the other emitting layer provides for direct charge trapping in the guest material. This DEL structure proved to be quite useful in achieving the reported device characteristics.
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NHK Laboratories Note No.513
A YC-separation-type projector: High dynamic range with double modulation

Yuichi Kusakabe, Masaru Kanazawa, Yuji Nojiri, Masato Furuya*1, Makoto Yoshimura*1
*1:Victor Company of Japan, Ltd., Kanagawa, Japan
Journal of the Society for Information Display, Vol.16, No.2, pp.383-391

An experimental projector that features double modulation to obtain high-resolution (4096×2160 pixels) and high-dynamic-range images has been developed. Although a conventional projector contains three modulators for red, green, and blue and outputs light after combining the modulated light from these three sources, our projector has an additional modulator for luminance that modulates the combined RGB modulated light. It can display high-resolution color images by combining three low-resolution panels for chrominance modulation and one high-resolution panel for luminance modulation. In addition, the dynamic range is dramatically improved because the double-modulation scheme minimizes black levels in projected images. The projector demonstrates an extremely high dynamic range of 1.1 million to 1 and 10-bit tone reproduction.
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Copyright©2008 Society for Information Display 1071-0922/08/1602-0383$1.00

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