Answers are grounded in this paper and cite their sources.
The morphological change of vapor-deposited TPD (N,N′-diphenyl-N,N′-bis-(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine) films, used as the hole transport layer of organic electroluminescent (EL) devices, on a glass plate was observed by atomic force microscopy (AFM) and friction force microscopy (FFM) in an ambient atmosphere. The TPD film was flat and amorphous as deposited, but was crystallized partially about a week later. By friction force loop measurement, we found that the bare glass surface was revealed between the crystals and between the amorphous film and the crystal due to mass transport for crystallization of TPD from the amorphous film.
No takes yet. Share an insight, caveat, or question.
Han et al. (1994) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: