Improved lifetime of an OLED using aluminum (III) tris (8-hydroxyquinolate)

Abstract

Improved lifetime with enhanced efficiency of an Alq₃ based OLED was realized by the co-evaporation of hexamethylbenzene (HMB). Two different solvated crystalline systems of Alq₃, Alq₃(C₇H₈)_1/2, Alq₃(C₂H₅OH), were synthesized to investigate the effect of optically inactive materials on the emission properties of Alq₃. Clathrate solvents perturb the excited electronic states of Alq₃ so that the incorporated materials in OLEDs should be chemically and optically inactive to control polymorphs. HMB acts as a carrier blocker for both electrons and holes. However, Alq₃ may be stabilized from Joule heat if the Joule heat is efficiently consumed as the vibrational/rotational energy of HMB. Consequently, the self-quenching and the crystallization of Alq₃ are effectively suppressed by the HMB, resulting in prolonged operating time and enhanced efficiency for Alq₃-OLEDs.

Keywords::

• Alq₃
• Organic EL
• Lifetime
• Hexamethylbenzene