title: Degradation of Flexible, ITO-Free Oligothiophene Organic Solar Cells.
abstract: We investigate the degradation of organic solar cells based on an oligothiophene (DCV5T-Me) small molecule donor and the acceptor C60. Two different flexible, transparent bottom electrode types are employed: a transparent metal electrode (TME) and silver nanowires (AgNWs). They exhibit high optical transparency up to 86% and a sheet resistance as low as 12Ω/□. Power conversion efficiencies of 7.0%, 5.7%, and 7.2% on TME, AgNWs, and indium tin oxide (ITO, reference) are reached, respectively. The solar cells are protected against moisture ingress utilizing a flexible alumina thin-film, exhibiting water vapor transmission rates down to 3 × 10(-5) g m(-2) day(-1) at 38 °C and 90% relative humidity (RH). Implementation of this ultrabarrier as top and bottom encapsulation enables fabrication of fully flexible devices. A decrease in PCE to 80% of initial values is observed after 1000 ± 50 h on flexible, encapsulated TME but only 20 ± 5 h on AgNWs in a climate of 38 °C/50% RH. Degradation in AgNW-based devices is attributed to electrode decomposition.
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , George-Bähr-Straße 1, 01069 Dresden, Germany.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Bormann
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , George-Bähr-Straße 1, 01069 Dresden, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Nehm
authors.affiliation: Physikalische Chemie, Technische Universität Dresden , Bergstraße 66b, 01062 Dresden, Germany.|Cluster of Excellence Center for Advancing Electronics Dresden (CFAED), Technische Universtität Dresden , Würzburger Staße 46, 01187 Dresden, Germany.
authors.forename: Luisa
authors.initials: L
authors.lastname: Sonntag
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , George-Bähr-Straße 1, 01069 Dresden, Germany.
authors.forename: Fan-Yu
authors.initials: FY
authors.lastname: Chen
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , George-Bähr-Straße 1, 01069 Dresden, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Selzer
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , George-Bähr-Straße 1, 01069 Dresden, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Müller-Meskamp
authors.affiliation: Physikalische Chemie, Technische Universität Dresden , Bergstraße 66b, 01062 Dresden, Germany.|Cluster of Excellence Center for Advancing Electronics Dresden (CFAED), Technische Universtität Dresden , Würzburger Staße 46, 01187 Dresden, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Eychmüller
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , George-Bähr-Straße 1, 01069 Dresden, Germany.|Fellow of the Canadian Institute for Advanced Research (CIFAR) , 180 Dundas Street West, Toronto, Ontario, Canada M5G 1Z8.
authors.forename: Karl
authors.initials: K
authors.lastname: Leo
keywords: degradation; encapsulation; flexible; oligothiophene; organic solar cells; silver nanowires; transparent metal electrode