Substituted Aluminum and Zinc Quinolates with Blue-Shifted Absorbance/Luminescence Bands: Synthesis and Spectroscopic, Photoluminescence, and Electroluminescence Characterization
文摘
Two novel lumophores based on aluminum and zincmetallo-8-hydroxyquinolates havebeen prepared as electroluminescent materials, and their absorbance,photoluminescence,and electroluminescence properties compared with unsubstituted versionsof these samecomplexes. 8-Hydroxy-5-piperidinylquinolinesulfonamide(1) was synthesized in order toadd an electron-withdrawing substituent at the 5-position in8-hydroxyquinoline, increasingthe solubility of the corresponding metal quinolate complexes innonpolar solvents, andproducing a blue-shift in the emission wavelength maximum, relative tocomplexes formedfrom the unsubstituted compound. The aluminum complex(Al(QS)3) and the zinc complex(Zn(QS)2) of 1 were compared with thealuminum and zinc complexes of unsubstituted8-hydroxyquinoline (AlQ3 and ZnQ2), both assolutions and as pure thin films, or as poly(N-vinylcarbazole) (PVK) thin films doped with the metalquinolates. Ultraviolet photoelectron spectroscopy data are presented to assist in estimating theenergies of the highestoccupied molecular orbitals (HOMO) of AlQ3,ZnQ2, Al(QS)3, andZn(QS)2. Electroluminescence data shows that ITO/Al(QS)3-PVK/aluminum andITO/Zn(QS)2-PVK/aluminumdevices exhibit good diode-like electrical behavior.Electroluminescence spectra mimic thephotoluminescence spectra for all complexes.