Solution-processible small molecular organic light-emitting diode material and devices based on the substituted aluminum quinolate

Abstract

We have discovered a new type of small molecular host material based on aluminum(III) 8-hydroxyquinolates, Al(Saq)(3), which was synthesized with three 5-(N-ethylanilinesulfonamide)-8-quinolinoline as bidentate ligands. By X-ray diffraction crystallographic analysis, the crystals of meridional Al(Saq)(3) are monoclinic, space group P2(1)/c, a = 17.952(3) Angstrom, b = 17.7160 Angstrom, c = 17.080(3) Angstrom, beta = 99.895(4)degrees. Its peak photoluminescence in solid phase appears at 488 nm. Its LUMO/HOMO (-3.13/-6.04 eV) and optical band gap (E-g 2.91 eV) were determined by cyclic voltammetry. In solid thin film morphological investigation, it shows good thermal properties and high quantum efficiency. When doped with 0.7 wt % of the high fluorescent green dopant 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo-[l]pyrano[6,7,8-ij]quinolizin-11-one (C-545T), energy transfer from Al-(Saq)(3) to dopant will occur and high green light emission can be achieved. For fabrication of OLEDs using spin-coating techniques, its electroluminescence is at 1931 CIEx,y (0.21, 0.41).