Lithium tetra-(8-hydroxy-quinolinato) boron for blue electroluminescent applications

Abstract

We report the optical and electroluminescent properties of the organometallic complex lithium tetra-(8-hydroxy-quinolinato) boron (LiBq4). The complex was prepared by the reaction of lithium borohydride with 8-hydroxyquinoline and shows absorption cutoff wavelength of 410 nm and bright blue photoluminescence with a peak wavelength at 466 nm. The ionization potential of LiBq4 was determined to be ∼5.6 eV by a photoemission apparatus. Electroluminescence (EL) properties of three-layer light-emitting diodes (LED) of ITO/PVK:TPD/LiBq4/Alq3/Mg with LiBq4 as the active layer were characterized. The EL spectra of the three-layer device are similar to the PL spectrum of the single layer LiBq4 but with peak wavelength at 475 nm. The results indicate that boron complexes are potential blue emitters for LED applications.