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.
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