Photoinduced electron transfer in multilayer films composed of conjugated polyelectrolyte and amphiphilic copolymer hosting electron acceptor molecules

Ultrathin multilayer films composed of conjugated anionic polyelectrolyte, poly(8-(3-thienyl)octanosulfonate) (P3TOSNa), and positively charged poly(N,N-dimethyl-N-4′-vinylbenzyl-N-2-(decanoyl-N′-methylimino) ethylammonium chloride)-co-(N,N,N-trimethyl-N-4′-vinylbenzylammonium chloride) (Ak-St-H) have been fabricated using the layer-by-layer technique. UV-Vis spectroscopy, atomic force microscopy and spectroscopic ellipsometry were applied for thickness and morphology characterization revealing regular growth and smooth surfaces of the films. An electron accepting molecule (butyl viologen) was then successfully entrapped inside the hydrophobic domains formed by Ak-St-H via a solubilization procedure. Photoinduced electron transfer from P3TOSNa polymer to butyl viologen molecules has been observed inside the nanostructured multilayers as confirmed by steady-state fluorescence spectroscopy and time-resolved fluorescence decay measurements. The structure of this water-born film helps to protect the hydrophobic acceptor molecules from aggregation and enables efficient charge separation within the film that is one of the crucial steps in organic photovoltaic systems.