title: Impact of mesoscale order on open-circuit voltage in organic solar cells.
abstract: Structural order in organic solar cells is paramount: it reduces energetic disorder, boosts charge and exciton mobilities, and assists exciton splitting. Owing to spatial localization of electronic states, microscopic descriptions of photovoltaic processes tend to overlook the influence of structural features at the mesoscale. Long-range electrostatic interactions nevertheless probe this ordering, making local properties depend on the mesoscopic order. Using a technique developed to address spatially aperiodic excitations in thin films and in bulk, we show how inclusion of mesoscale order resolves the controversy between experimental and theoretical results for the energy-level profile and alignment in a variety of photovoltaic systems, with direct experimental validation. Optimal use of long-range ordering also rationalizes the acceptor-donor-acceptor paradigm for molecular design of donor dyes. We predict open-circuit voltages of planar heterojunction solar cells in excellent agreement with experimental data, based only on crystal structures and interfacial orientation.
authors.affiliation: 1] Max Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany [2] Heidelberg Graduate School of Fundamental Physics, INF 226 69120 Heidelberg, Germany.
authors.forename: Carl
authors.initials: C
authors.lastname: Poelking
authors.affiliation: Institut für Angewandte Photophysik, George-Bähr-Straße 10 01062 Dresden, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Tietze
authors.affiliation: Institut für Angewandte Photophysik, George-Bähr-Straße 10 01062 Dresden, Germany.
authors.forename: Chris
authors.initials: C
authors.lastname: Elschner
authors.affiliation: Physikalische Chemie, Universität zu Köln, Luxemburger Straße 116 50939 Köln, Germany.
authors.forename: Selina
authors.initials: S
authors.lastname: Olthof
authors.affiliation: Physikalische Chemie, Universität zu Köln, Luxemburger Straße 116 50939 Köln, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Hertel
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Baumeier
authors.affiliation: Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Würthner
authors.affiliation: Physikalische Chemie, Universität zu Köln, Luxemburger Straße 116 50939 Köln, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Meerholz
authors.affiliation: Institut für Angewandte Photophysik, George-Bähr-Straße 10 01062 Dresden, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Leo
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany.
authors.forename: Denis
authors.initials: D
authors.lastname: Andrienko