title: High-efficiency tris(8-hydroxyquinoline)aluminum (Alq3) complexes for organic white-light-emitting diodes and solid-state lighting.
abstract: Combinations of electron-withdrawing and -donating substituents on the 8-hydroxyquinoline ligand of the tris(8-hydroxyquinoline)aluminum (Alq(3)) complexes allow for control of the HOMO and LUMO energies and the HOMO-LUMO gap responsible for emission from the complexes. Here, we present a systematic study on tuning the emission and electroluminescence (EL) from Alq(3) complexes from the green to blue region. In this study, we explored the combination of electron-donating substituents on C4 and C6. Compounds 1-6 displayed the emission tuning between 478 and 526 nm, and fluorescence quantum yield between 0.15 and 0.57. The compounds 2-6 were used as emitters and hosts in organic light-emitting diodes (OLEDs). The highest OLED external quantum efficiency (EQE) observed was 4.6%, which is among the highest observed for Alq(3) complexes. Also, the compounds 3-5 were used as hosts for red phosphorescent dopants to obtain white light-emitting diodes (WOLED). The WOLEDs displayed high efficiency (EQE up to 19%) and high white color purity (color rendering index (CRI≈85).
authors.affiliation: Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
authors.forename: César
authors.initials: C
authors.lastname: Pérez-Bolívar
authors.forename: Shin-ya
authors.initials: SY
authors.lastname: Takizawa
authors.forename: Go
authors.initials: G
authors.lastname: Nishimura
authors.forename: Victor A
authors.initials: VA
authors.lastname: Montes
authors.forename: Pavel
authors.initials: P
authors.lastname: Anzenbacher