Photoluminescence characteristics of green and blue emitting Alq3 organic molecules in crystals and thin films

Alq(3) is synthesized by mixing 8-quinolinol and Al(OH)(3) in distilled water at about 95 degrees C. The reaction time of 24 and 100 h leads to alpha- and gamma-rich Alq(3), respectively. The alpha-rich Alq(3) is converted to gamma-Alq(3) after annealing at 400 degrees C, while sublimation at 330 degrees C destroys gamma-Alq(3). The mer- and fac-isomers give the same vibronic structure in the photoluminescence (PL) spectra at 12 K, which is composed of a progression of vibrational energy of 660 cm (1), but the PL band peak of fac-isomer is blue-shifted by about 34 nm with respect to that of mer-isomer. When the temperature is increased from 12 K to 296 K, the PL intensity is observed to decrease above 100 K by non-radiative bimolecular recombination. (C) 2010 Elsevier B.V. All rights reserved.