Nanoscale study on origins of the bright clusters in/on moisture-exposed tris(8-hydroxyquinoline) aluminum thin films

By exploiting variable-temperature tapping mode atomic force microscopy (VT-AFM), along with X-ray diffraction (XRD) and Fourier transform infrared spectroscopy, we have systematically investigated the nature of the bright clusters, which can be classified as protrusion and grown grain, in/on the moisture-exposed tris(8-hydroxyquinoline) aluminum (Alq 3) thin film. The experimental results suggest that the protrusion is most likely to be a hydrated Alq 3 species, whereas the grown grain is a crystalline Alq 3 structure. Moreover, the evolution of a hydrated Alq 3 species into a dark hole and/or a crystalline Alq 3 structure was in-situ visualized.