Ji-Geun Jang

Thin LED light module using the inclined edge and inhomogeneous pattern reflection of a light guide plate

A low-power, high-brightness, thin, and flat LED light module was fabricated. LED arrays attached to the four walls of the lower part of a light guide plate (LGP) were used as the light source. The LGP was composed of a lower part with dot patterns on the bottom side, an intermediate section with inclined edges for the reduction of the bezel area, and a light-exiting plate. The bottom sides of the inclined edges and lower plate were coated with metal films for light reflection. The dot patterns on the bottom side of the lower plate were more concentrated in the center to obtain uniform brightness by inhomogeneous reflection. The dimensions of the fabricated LED light module were 100 mm (L) × 100 mm (W) × 10 mm (T). The average brightness and luminous uniformity of the LED light module were 12,155 cd/m2 and 96.7%, respectively.

Two Wavelength OLED with the Stacked GDI602(691)/ GDI602(Rubrene) Fluorescent Layer

A new organic light emitting device(OLED) with two peak wavelength(blue and yellow) emission was fabricated using the selective doping in a single fluorescent host , and its electrical and optical characteristics were investigated. The fabricated device showed the luminance and efficiency of 1600 Cd/m 2 and 2.4 lm/W under the applied voltage of 10V, respectively. And its electroluminescent spectra had two peak wavelengths of 470nm and 560nm emitting bluish white light. The OLED with dual wavelength emission in this experiment is likely to be developed as a white OLED with simpler fluorescent system than conventional devices.

Fabrication and Characterization of Blue OLED using GDI Host-Dopant Phosphors

The blue emitting OLEDs using GDI host-dopant phosphors have been fabricated and characterized. In the device fabrication, 2-TNATA [4,4`,4`-tris(2-naphthylphenyl-phenylamino)- triphenylamine] as a hole injection material and NPB [N,N`-bis(1-naphthyl)-N,N`-diphenyl-1,1`-biphenyl-4,4`-diamine] as a hole transport material were deposited on the ITO(indium thin oxide)/glass substrate by vacuum evaporation. And then, blue color emission layer was deposited using GDI602 as a host material and GDI691 as a dopant. Finally, small molecule OLEDs with structure of ITO/2-TNATA/NPB/GDI602:GDI691/Alq3/LiF/Al were obtained by in-situ deposition of Alq3, LiF and Al as the electron transport material, electron injection material and cathode, respectively. Blue OLEDs fabricated in our experiments showed the color coordinate of CIE(0.14, 0.16) and the maximum power efficiency of 1.1 lm/W at 11 V with the peak emission wavelength of 464 nm.

New White OLED Using Selective Dopingin a Single Host

A new white emitting OLED (WOLED) using selective doping in a single host is proposed. The device had the structure of ITO/2-TNATA/NPB/GDI-602/GDI602:rubrene/Alq3/LiF/Al, in which the GDI602/GDI602:rubrene emission layer was prepared by the selective doping of rubrene into the single GDI-602 host material. The blue and yellow emitting regions consisted of GDI-602 that was undoped and doped with rubrene (10% of the host material in the evaporation rate), respectively. The luminance and efficiency of the fabricated device were 1050 cd/m2 and 0.6 lm/W at the driving voltage of 9 V, respectively. It showed two peak wavelength emissions of 460 nm and 560 nm in the electroluminescent spectra. The color coordinate in the CIE chart was (0.33, 0.33) which proved to be pure white emission.