title: High-resolution noncontact AFM and Kelvin probe force microscopy investigations of self-assembled photovoltaic donor-acceptor dyads.
abstract: Self-assembled donor-acceptor dyads are used as model nanostructured heterojunctions for local investigations by noncontact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). With the aim to probe the photo-induced charge carrier generation, thin films deposited on transparent indium tin oxide substrates are investigated in dark conditions and upon illumination. The topographic and contact potential difference (CPD) images taken under dark conditions are analysed in view of the results of complementary transmission electron microscopy (TEM) experiments. After in situ annealing, it is shown that the dyads with longer donor blocks essentially lead to standing acceptor-donor lamellae, where the acceptor and donor groups are π-stacked in an edge-on configuration. The existence of strong CPD and surface photo-voltage (SPV) contrasts shows that structural variations occur within the bulk of the edge-on stacks. SPV images with a very high lateral resolution are achieved, which allows for the resolution of local photo-charging contrasts at the scale of single edge-on lamella. This work paves the way for local investigations of the optoelectronic properties of donor-acceptor supramolecular architectures down to the elementary building block level.
authors.affiliation: University Grenoble Alpes, INAC-SPrAM, 38000 Grenoble, France; CNRS Alpes, INAC-SPrAM, 38000 Grenoble, France; CEA, INAC-SPrAM, 38000 Grenoble, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Grévin
authors.affiliation: Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France; Institut für Organische Chemie II und Neue Materialien, Ulm Universität, Albert-Einstein-Allee 11, Ulm, Germany.
authors.forename: Pierre-Olivier
authors.initials: PO
authors.lastname: Schwartz
authors.affiliation: Institut Charles Sadron, CNRS, Université de Strasbourg, 23 rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Biniek
authors.affiliation: Institut Charles Sadron, CNRS, Université de Strasbourg, 23 rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Brinkmann
authors.affiliation: Institut de Chimie et Procédés pour l'Energie, l'Environnement et la santé (ICPEES), Université de Strasbourg, CNRS UMR 7515, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Leclerc
authors.affiliation: Institut de Chimie et Procédés pour l'Energie, l'Environnement et la santé (ICPEES), Université de Strasbourg, CNRS UMR 7515, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France.
authors.forename: Elena
authors.initials: E
authors.lastname: Zaborova
authors.affiliation: Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Méry
keywords: Kelvin probe force microscopy (KPFM); donor–acceptor co-oligomers; donor–acceptor lamellae; donor–acceptor-ordered bulk heterojunction; noncontact atomic force microscopy (nc-AFM); organic photovoltaics; surface photo-voltage (SPV)