Kyu Hwan Hwang

Optically bifacial thin-film wire-grid polarizers with nano-patterns of a graded metal-dielectric composite layer

We report on the concept of a thin film wire-grid polarizer (WGP) with optically dual characteristics by introducing a nano-patterned graded metal-dielectric composite-material layer. The Ti-SiO(2) composite layer with a depth profile of a gradually-varied composition ratio shows an absorptive feature due to the elimination of an optical interface between a metal and a glass substrate, while the metal side of the WGP gives a reflective character. The unprecedented optically-bifacial thin-film WGP with the 144 nm-period straight-line patterns of a 100 nm-thick Ti-SiO(2) composite layer and a 185 nm-thick Al layer shows the exceptionally low reflectance below 15 % from the absorptive side and the high polarization extinction ratio (PER) of over 500 at 550 nm, which is acceptable for use as various display applications such as AMOLEDs and LCDs.

11.3: Distinguished Paper: LTPSbased Transparent AM OLED

14.1” qFHD quarter Full High Definition Transparent Active Matrix Organic Light Emitting Display AM OLED was developed with the well known and reliable technology based on LTPS Low Temperature Poly Silicon backplane. The key concept of the transparent AM OLED display lies on the seethrough window on each pixel so that the objects across the device can be seen. In the design of pixel structure, functional separation of light emitting area and seethrough area was realized on the different regions. The features of transparency and transmitted image quality were investigated and optimized in the design of the pixel structure. Up to 38% transparency of the prototype panel was accomplished with the high transparent cathode material which transmittance was more than 75%. LTPS based Active Matrix and Top emission OLED structure was used for the prototype to provide wide range of color expression, more than 100% of color gamut.

Publisher's Note: Efficient Inverted Top-Emitting Organic Light Emitting Diodes with Transparent and Surface-Modified Multilayer Anodes [ Electrochem. Solid-State Lett. , 13 , J43 (2010) ]

Publisher’s Note: Efficient Inverted Top-Emitting Organic Light Emitting Diodes with Transparent and Surface-Modified Multilayer Anodes [Electrochem. Solid-State Lett., 13, J43 (2010)] Seung Yoon Ryu, Chang Ho Lee, Il Soo Oh, Seung Yong Song, Kyu Hwan Hwang, Hyeon Seok Hwang, Man Hyeop Han, Byoung Har Hwang, Hong Koo Baik, Youn Sang Kim, and Jun Yeob Lee Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea Samsung Mobile Display, Company, Limited, Yongin-City, Gyeonggi 449-577, Korea Department of Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-742, Korea Department of Polymer Science and Engineering, Dankook University, Yongin-City 448-701, Korea

Weak-microcavity organic light-emitting diodes with improved light-extraction and wide viewing-angle

We propose and demonstrate weak-microcavity organic light-emitting diode (OLED) displays that deliver both a high light-extraction efficiency and wide viewing-angle characteristics. A single pair of low- and high-index layers is inserted between indium tin oxide (ITO) and a glass substrate. The electroluminescent (EL) efficiencies of discrete red, green, and blue weak-microcavity OLEDs (WMOLEDs) are enhanced by 56%, 107%, and 26%, respectively with minimal changes viewing angle and EL spectra characteristics. The color purity is also improved for all three colors. Moreover, we fabricated full-color 128×160 passive-matrix bottom-emitting WMOLED displays to prove their manufacturability. This design is realized by simple one-step 20-nm etching of the low-index layer of red/green subpixels. The EL efficiency of white color in the WMOLED display is 27% higher than that of a conventional OLED display.