Ternary zinc complexes as electron transport and electroluminescent materials

Ternary zinc complexes: [2-(2-hydroxyphenyl) benzoxazolato] 5-chloro-8-hydroxy quinolinatozinc(II) [Zn(HPB)(Clq)] and [2-(2-hydroxyphenyl) benzoxazolato] 5,7-dichloro-8-hydroxyquinolinatozinc(II) [Zn (HPB)(Cl(2)q)]) were synthesized and characterized as electroluminescent materials. These complexes possessed high thermal stability (>300 degrees C) and high glass transition temperature (>150 degrees C). The excited state lifetime of these complexes measured by transient photo-luminescence spectroscopy showed 4.19, 11.02 ns and 2.67, 10.7 ns for Zn(HPB)(Clq) and Zn(HPB)(Cl(2)q), respectively. The electroluminescence spectra showed peak emission centered at 549 and 554 nm, respectively, for these materials. Both the molecules were found to be quite efficient in a multilayered device structure ITO/alpha-NPD/Zinc complex/BCP/Alq(3)/LiF/Al with yellow emission having Internationale d'Eclairage (CIE) coordinates x = 0.37 and y = 0.57 for Zn(HPB)(Clq); and x = 0.40 and y = 0.56 for the Zn(HPB)(Cl(2)q) complex. Electron mobilities of these molecules were found to be 3 x 10(-6)-7 x 10(-6) s for electric field range 1000 -1200 (V/cm)(1/2). These molecules showed very high efficiency as electron transport layer with device structure ITO/alpha-NPD/5% Ir(ppy)(3) doped CBP/BCP/Zn(HPB)(Clq) or Zn(HPB)(Cl(2)q)/LiF/Al and therefore are better electron transporters as compared to Alq(3) in a device structure of ITO/alpha-NPD/5% Ir(ppy)(3) doped CBP/BCP/Alq(3)/LiF/Al

Optoelectronic characterization of zinc complexes for display device applications

2-(2-Pyridyl)benzimidazolato)-2-methyl-8-hydroxyquinolinatozinc(II)[ZnPBI(Meq)], 2-(2-pyridyl)benzimidazolato)-5-chloro-8-hydroxyquinolinatozinc(II) [ZnPBI(Clq)] and 2-(2-pyridyl)benzimidazolato)-8-hydroxyquinolinatozinc(II) [ZnPBI(q)] were synthesized and characterized for the purpose to be used as electroluminescent materials. All complexes emitted bright colored light on excitation by ultra-violet light source which showed their suitability for the operation in opto-electronic devices. Using a selected complex [ZnPBI(Meq)] as emissive layer, multilayered organic electroluminescent device was fabricated having structure ITO/alpha-NPD/Zinc complex/BCP/Alq(3)/LiF/Al, that produced bright bluish green emission at 532 nm. Maximum luminescence observed was 4038 cd/m(2) at 18 V while the turn on voltage of the device was 7 V. The Commission Internationale d'Eclairage chromaticity of the device had color coordinates at x = 0.35, y = 0.44 and was found to be independent of the operating voltages. The [ZnPBI(Meq)] complex exhibited high thermal stability (> 300 A degrees C) and high glass transition temperature (> 150 A degrees C)

Synthesis, Characterization, and Electroluminescent Characteristics of Mixed-Ligand Zinc(II) Complexes

Mixed-ligand zinc complexes, i.e., 2-(2-hydroxyphenyl)benzothiazolato-5,7- dichloro-8-hydroxyquinolinato zinc(II) [ZnBTZ(Cl(2)q)], 2-(2-hydroxyphenyl) benzothiazolato-5,7-dimethyl-8-hydroxyquinolinato zinc(II) [ZnBTZ(Me(2)q)], and 2-(2-hydroxyphenyl)benzothiazolato-2-carbonitril-8-hydroxyquinolinato zinc(II) [ZnBTZ(CNq)], were synthesized and characterized. The metal complexes have high thermal stability (> 300A degrees C) and high glass-transition temperature (> 150A degrees C) and are suitable for optoelectronic applications. Optical properties of the synthesized complexes were characterized by using ultraviolet-visible (UV-Vis) and photoluminescence spectroscopy. Color tuning by changing the ligand was observed in synthesized complexes. Multilayered organic electroluminescent devices were fabricated having structure indium-tin oxide (ITO)/N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (alpha-NPD)/zinc complex/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/tris(quinolinolate)Al-III (Alq(3))/LiF/Al using the synthesized complexes as emissive material. The electroluminescence spectra show peak emission centered at 532 nm, 572 nm, and 541 nm, respectively, for these materials. The emitted light has chromaticity with Commission Internationale d'A parts per thousand clairage coordinates x = 0.35 and y = 0.56 for ZnBTZ(Cl(2)q), x = 0.49 and y = 0.47 for ZnBTZ(Me(2)q), and x = 0.48 and y = 0.40 for ZnBTZ(CNq) complex

Synthesis and Optical Characterization of Mixed Ligands Beryllium Complexes for Display Device Applications

Synthesis and photoluminescent behaviour of mixed ligand based beryllium complexes with 2-(2-hydroxyphenyl)benzoxazole (HPB) and 5-chloro-8-hydroxyquinoline (Clq) or 5,7-dichloro-8-hydroxyquinoline (Cl2q) or 2-methyl-8-hydroxyquinoline (Meq) or 8-hydroxyquinoline (q) are reported in this work. These complexes, that is, [BeHPB(Clq)], [BeHPB(Cl2q)], [BeHPB(Meq)], and [BeHPB(q)], were prepared and their structures were confirmed by elemental analysis, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and thermal analysis. The beryllium complexes exhibited good thermal stability up to ~300°C temperature. The photophysical properties of beryllium complexes were studied using ultraviolet-visible absorption and photoluminescence emission spectroscopy. The complexes showed absorption peaks due to π-π∗ and n-π∗ electronic transitions. The complexes emitted greenish blue light with peak wavelength at 496 nm, 510 nm, 490 nm, and 505 nm, respectively, consisting of high intensity. Color tuning was observed with changing the substituents in quinoline ring ligand in metal complexes. The emitted light had Commission Internationale d’Eclairage color coordinates values at x=0.15 and y=0.43 for [BeHPB(Clq)], x=0.21 and y=0.56 for [BeHPB(Cl2q)], x=0.14 and y=0.38 for [BeHPB(Meq)], x=0.17 and y=0.41 for [BeHPB(q)]. Theoretical calculations using DFT/B3LYP/6-31G(d,p) method were performed to reveal the three-dimensional geometries and the frontier molecular orbital energy levels of these synthesized metal complexes