Formation of fluorescence reliefs photocontrolled by collective mass migration

Abstract

Fluorescent and photochromic non-doped thin films have been elaborated from bifunctional molecules exhibiting time-stable glassy properties and combining each a photoisomerizable azo unit covalently linked to a fluorescent moiety through a rigid, saturated and bulky spacer. Photoillumination under polarized light led to the rise of periodically structured emissive reliefs. The microscopic emission modulation was addressed by fluorescence confocal microscopy, and the maxima in emission correlated with the minima in transmission. This clear correspondence features the physical displacement of the fluorophore units, pulled by the azo moieties during their photoinduced motion in the bulk; this accumulation of fluorescent materials followed the impinging light pattern, and could be erased and promoted again under specific illumination conditions.