Jaekook Ha

11.4: Transparent AMOLED Display Based on Bottom Emission Structure

A transparent active matrix organic light emitting diode AMOLED display based on a bottom emission structure, which is best for largesized OLED displays, has been fabricated. The transparent AMOLED display shows an image only to its bottom side, and background images can be seen through the transmissive windows. Pixel layout of the conventional bottom emission structure has been redesigned to merge transmissive openings to a single window per each pixel for higher transmissivity. A prototype of the transparent AMOLED display demonstrated 27% transmissivity and 100% NTSC color gamut.

25.4: Advances and Issues in White OLED and Color Filter Architecture

Since the scalability of OLED process is crucial factor for TV application, white OLED with color filter has been developed for large-Size AMOLED panel. Despite of recent technology advancement enabling high color purity, large-Sized AMOLED, a lot of problems to solve still exist to enter the large-Sized display market. Here, Samsung will discuss what has been concerned for large panel and how far the OLED technologies need to go for the marketplace of large-Sized display.

Excimer emission in electroluminescence and photoluminescence of polyfluorene derivatives: Effects of local heating and exciton density

We report a study of excimer emission from copolymers of dibutylfluorene and butylphenylphenoxazine. Temperature dependence of photoluminescence (PL) spectra measured from room temperature to above glass transition temperature, and excitation power dependence of PL spectra reveal that the observed differences in excimer intensity between PL and electroluminescence spectra are neither solely due to local heating by electric current nor to differences in exciton density. Instead, different nature of the excitations upon photoexcitation and excitation by passing current has to be considered to explain the different behavior.

68.2: Achieving High Color Gamut with Microcavity on White OLED

We have demonstrated bottom-emission white OLED devices, which have RGBW sub-pixel and high color gamut over 100% NTSC ratio with White-to-Green microcavity technique. Large-Sized AMOLED TV has to show very high quality display images to overcome LCD TV. However, the R, G and B colors filtered by LCD color-filters are not saturated enough. Especially, green emission peak is very broad because blue emission peak is not removed perfectly by green color-filter. Therefore, we fabricate white OLED having saturated green color by adapting microcavity technique. The results of green pixels are (0.211, 0.723) in color coordinates, and the efficiency of green is 15.4 cd/A, which was (0.217, 0.600) and 7.5 cd/A. And the color gamut with microcavity reaches more than 100% NTSC.

54.4: Highly Efficient and Wide Color Gamut White OLED Architecture for Display Application

Highly efficient WOLEDs, with the efficiencies of 19 cd/A, 16 cd/A, and 33 cd/A and CIE color coordinates of (0.25, 0.35), (0.30, 0.32), and (0.30, 0.32) respectively, have been developed. The broad white emitting TE-WOLEDs for high resolution display have been realized by controlling the microcavity between the cathode and anode. 96 % of NTSCx,y ratio was achieved from the TE-WOLED with the optical path control layer (OPCL) and new green color filter (CF).

CHEMICAL DOPING OF TRIPHENYLAMINE-BENZALDEHYDE POLYMERS

A series of different benzaldehydes-4-tolyldiphenylamine polymers has been oxidized by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tetrachloro-1,4-benzoquinone (p-chloranil), and also doped by 10-camphorsulfonic acid in order to increase their conductivity. The doped polymers were characterized by 1H NMR spectroscopy, cyclic voltammetry, UV, and IR spectroscopy. It was found by 1H NMR spectroscopy that the oxidation yield increased with the increased amount of oxidation agent. It was shown that optical and electrochemical bandgaps of the polymers decreased after oxidation. Conductivity measurements revealed that the applied oxidation and doping procedure resulted in decreased electrical resistance of their initial polymers, down to the level of semiconducting materials. An increased thermal stability of the polymer after oxidation was confirmed by differential scanning calorimetry.

18.5: Efficient Tandem White OLED Devices for Medical Display Applications

White OLED devices have been electrically and optically optimized for medical display applications. Efficiencies of 51.9 cd/A and 33.3 cd/A at ∼7,500K have been achieved for threecolor and twocolor white, respectively. These devices are applied in panels to achieve high contrast and low power consumption compared to LCD medical displays.

P-228: Degradation of White Light Emitting OLEDs

We firstly report the degradation analysis of multilayer structured WOLED by using spectroscopic and microscopic analytical methods. Our analytical results demonstrated that the interface between cathode and electron-transporting layer is responsible for the intrinsic long-term degradation of WOLEDs.