Gweon Young Ryu

Dependence of Effective Doping Concentration on the Molecular Structure of Dopant: ABCV-P Doped OLEDs with Broad Range of and High Doping Concentration

A new red fluorescent material, (2Z,2′Z)-3,3′-[4,4″-bis(dimethylamino)-1,1′:4′,1″-terphenyl-2′,5′-diyl]bis(2-phenylacrylonitrile) (ABCV-P), preventing concentration quenching in solid state was synthesized. Studies on the device performance of ABCV-P doped OLEDs with variation of the doping concentration and thickness of the emitting layer as well as the optical properties of ABCV-P were carried out. The effective doping concentration of ABCV-P dopant was in the range of 40%–50%. ABCV-P doped OLEDs showed maximum luminance of 11000 cd/m2 (40%) and 6800 cd/m2 (50%), CIExy coordinates of (0.588, 0.410) (40%) and (0.597, 0.402) (50%) and full width at half maxima of 71 nm and 72.5 nm, respectively. Accordingly, ABCV-P doped OLED showed much lower sensitivity to doping concentration than the typical red doped ones.

The Effects of Molecular Structure on Surface Morphology of Thin Film and Optoelectronic Property of a Fluorophore

A yellow fluorescent material, (2Z)-3-[4,4′′-bis(dimethylamino)-1,1′:4′,1′′-terphenyl-2′-yl]-2-phenylacrylonitrile was synthesized in order to investigate the effect of molecular structure on surface morphology of its thin film and its optoelectronic property. Atomic force microscopy measurment for thin films of 4-(dicyanomethylene)-2-methyl-6-(julolidin-4-yl-vinyl)-4H-pyran, (2Z)-3-[4,4′′-bis(dimethylamino)-1,1′:4′,1′′-terphenyl-2′-yl]-2-phenylacrylonitrile and (2Z,2′Z)-3,3′-[4,4′′-bis(dimethylamino)-1,1′:4′,1′′-terphenyl-2′,5′-diyl]bis(2-phenylacrylonitrile) represented that surface morphology of thin film of a fluorophore was dependent on its molecular structure such as coplanarity and molecular polarity. Surface morphology of thin film of BDAT-P showed much less amorphous than that of ABCV-P. Atomic force microscopy measurment for BDAT-P and ABCV-P was well corresponding to observed optoelectronic properties of them. The luminance of non-doped devices for BDAT-P and ABCV-P was measured to be 31.6 cd/m2 at 6 V and 249 cd/m2 at 6 V, respectively.