Effects of co-doping on the red fluorescent OLEDS.

The device performance of red organic light-emitting diodes (OLEDs) was dramatically improved by co-doping of the red fluorescent material of (2Z,2'Z)-3,3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2',5'-diyl]-bis(2-phenylacrylonitrile) (ABCV-P) with the hole transport material of N'-bis-(1-naphyl)-N,N'-diphenyl-1,1 '-biphenyl-4,4'-diamine (NPB) and the electron transport material of bis(2-methyl-8-quninolinato)-4-phenylphenolate aluminum (BAlq). The device structures were ITO/NPB/emitting layers/BAlq/Liq/Al in which the emitting layers were MADN:ABCV-P (40%) (device A), MADN:ABCV-P (40%):NPB (10%) (device B), MADN:ABCV-P (40%):BAlq (10%) (device C) and MADN:ABCV-P (40%):NPB (10%):BAlq (10%) (device D), respectively. The device D co-doped with NPB and BAlq exhibited maximum luminance of 9784 cd/m2, maximum luminous efficiency of 2.

The effect of the molecular structure on the optoelectronic properties of a fluorophore for use in organic light-emitting diodes.

A novel yellow light-emitting material, (2Z)-3-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2'-yl]-2-phenylacrylonitrile (BDAT-P), having the modified molecular structure from red fluorescent compound, (2Z, 2'Z)-3,3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2',5'-diyl]bis(2-phenylacry-lonitrile) (ABCV-P), was synthesized in order to study the effect of the molecular structure on the optoelectronic properties of a light-emitting material. UV-visible absorption and photoluminescence (PL) emission peaks measured in various solvent systems were summarized in Table I. In the respective solvent system, the bathochromic shift of PL emission peak relative to the peak of UV-visible absorption was much larger for ABCV-P with two electron donor-acceptor pairs than for BDAT-P with one electron donor-acceptor pair.

Substituent effect on color tuning of red light emission in photoluminescence and electroluminescence of red fluorophore.

Typical small red light-emitting molecules for organic light emitting diodes (OLEDs) were highly susceptible to fluorescence concentration quenching in solid state. Red fluorophores, (2Z, 2'Z)-3, 3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-29',5'-diyl]bis(2-phenylacrylonitrile) (ABCV-P), (2E, 2'E)-3,3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2',5'-diyl]bis[2-(2-thienyl)acrylonitrile] (ABCV-Th) and (2Z, 2'Z)-3,3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2',5'-diyl]bis[2-(2-naphthyl)acrylonitrile] (ABCV-Np), capable of preventing fluorescence concentration quenching were designed and synthesized. These compounds have intramolecular charge transfer (ICT) properties which were estimated by measurement of UV-Visible absorption and photoluminescence (PL) emission spectra with variation of solvent polarity (n-Hexane/Chloroform = 99/1, 1/1; Chloroform; Methylene chloride).