Improved photovoltaic performance of antracene-based polymer by solvent annealing method and methanol wash treatment

Özlem Usluer1,  Mamatimin Abbas2,  Sameh Boudiba3,  Lionel Hirsch2,  Daniel A. M. Egbe3
1Department of Energy Systems Engineering, Konya Necmettin Erbakan University, 42090, Meram, Konya, Turkey, 2Université Bordeaux, Laboratoire de l’Intégration du Matériau au Système (IMS), CNRS (UMR 5218), Site ENSCPB,16 avenue Pey Berland, 33607 Pessac Cedex, France, 3Linz Institute for Organic Solar Cells, Johannes Kepler University, Altenbergerstr. 69, 4040, Linz, Austria

Abstract

Anthracene-containing poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene) (PPE-PPV) polymer (AnE-PVstat) is promising material for organic solar cells, due to its optical band gap of about 2 eV, with high oxidation potential, resulting in generally high Voc in polymer solar cells when combined with [6,6]-phenyl C61 butyric acid methyl ester (PCBM).[1] In this work, AnE-PVstat polymer, equally equipped with linear octyl and branched 2-ethylhexyl side chains at the PPE and PPV parts, was synthesized according to a well established procedure which uses the Horner–Wadsworth–Emmons olefination reaction to polycondensate dialdehydes and bisphosphonate esters.[2] High performance organic solar cells were realized using this polymer as donor and PC60BM as acceptor by solvent annealing method and then methanol wash treatment on the active layer. Charge carrier mobilities of both electrons and holes in solvent annealed bulk heterojunction films of polymer and fullerene derivative mixture were studied using organic field effect transistors. Fine tuning of donor to acceptor ratio revealed optimum ratio around balanced mobilities, which led to highest power conversion effciency (PCE) of 4.02% in organic solar cells. Methanol wash approach further enhanced PCE to 4.65%.

References [1] Usluer, O.; Kastner, C.; Abbas, M.; Ulbricht, C.; Cimrova, V.; Wild, A.; Birckner, E.; Tekin, N.; Sariciftci, N. S.; Hoppe, H.; Rathgeber, S.; Egbe, D. A. M. J. Polym. Sci., Part A: Polym.Chem. 2012, 50, 3425. [2] Egbe, D. A. M.; Türk, S.; Rathgeber, S.; Kühnlenz, F.; Jadhav, R.; Wild, A.; Birckner, E.; Adam, G.; Pivrikas, A.; Cimrova, V.; Knör, G.; Sariciftci, N. S.; Hoppe, H. Macromolecules 2010, 43,1261.