title: Resonance light scattering in dye-aggregates forming in dewetting droplets.
abstract: Small organic semiconducting molecules assembling into supramolecular J- and H- aggregates have attracted much attention due to outstanding optoelectronic properties. However, their easy and reproducible fabrication is not yet sufficiently developed for industrial applications, except for silver halide photography. Here we present a method based on aggregate precipitation during the phase separation and dewetting of the evaporating dye precursor solution. The smaller the precursor droplets, the more pronounced the J-aggregation. The aggregates cause the films to resonantly scatter incoming light. Because the dye aggregate extinction resonances have narrowest bandwidths, a wavelength selectivity is observed that exceeds the selectivity of localized surface plasmon resonances. The aggregation mechanism can be easily applied to periodically structured substrates, making the method appealing for photonic applications. We demonstrate this point with a 2D grating, where the narrow absorption range of the aggregates leads to wavelength specific (one color only) scattering.
authors.affiliation: Laboratory for Functional Polymers, Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Tisserant
authors.forename: Rolf
authors.initials: R
authors.lastname: Brönnimann
authors.forename: Roland
authors.initials: R
authors.lastname: Hany
authors.forename: Sandra
authors.initials: S
authors.lastname: Jenatsch
authors.forename: Frank A
authors.initials: FA
authors.lastname: Nüesch
authors.forename: Raffaele
authors.initials: R
authors.lastname: Mezzenga
authors.forename: Gian-Luca
authors.initials: GL
authors.lastname: Bona
authors.forename: Jakob
authors.initials: J
authors.lastname: Heier
keywords: J-aggregates; PCBM; absorption grating; cyanine dye; dewetting; photonic crystal; resonant light scattering