Published online by Cambridge University Press: 10 February 2011
The morphological stability of evaporated films of aluminum(III) 8-hydroxyquinoline (Alq3) was investigated. Films which were found to be non-crystalline by x-ray diffraction upon deposition, crystallized rapidly upon annealing, especially where defects were present. Blends of Alq3with aluminum(III) 5-methyl-8-hydroxyquinoline were proposed for thermally stable amorphous emitting layers in light-emitting diodes. Films coevaporated at a 1:1 ratio did not show evidence of crystallization or phase separation even after long annealing periods at temperatures as high as 160°C.