title: Poly(4-vinylpyridine): A New Interface Layer for Organic Solar Cells.
abstract: Poly(4-vinylpyridine) (P4VP) was used as a cathode interface layer in inverted organic solar cells (OSCs) fabricated using poly[2,3-bis(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1) and PC71BM (phenyl C71butyric acid methyl ester) as the donor and acceptor materials, respectively. We successfully demonstrate that the work function of underlying indium tin oxide (ITO) electrode can be significantly reduced by ∼0.7 eV, after modification of the surface with a thin film of P4VP. Photoconversion efficiency of 4.7% was achieved from OSCs incorporating P4VP interface layer between the ITO and bulk heterojunction (BHJ). Thin P4VP layer, when used to modify ZnO electron transport layer in inverted OSCs, reduced the ZnO work function from 3.7 to 3.4 eV, which resulted in a noteworthy increase in open-circuit voltage from 840 to 890 mV. On simultaneous modification of ZnO with P4VP and optimization of the BHJ morphology by using solvent additive chloronapthalene, photoconversion efficiency of OSCs was significantly increased from 4.6% to 6.3%. The enhanced device parameters are also attributed to an energetically favorable material stratification, as a result of an enrichment of PC71BM toward the P4VP interface.
authors.affiliation: Future Industries Institute, University of South Australia , Adelaide, SA 5095, Australia.
authors.forename: Anirudh
authors.identifier: http://orcid.org/0000-0003-4841-0108
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Chemistry and Chemical Engineering, Chalmers University of Technology , SE-41296 Göteborg, Sweden.
authors.forename: Renee
authors.initials: R
authors.lastname: Kroon
authors.affiliation: Flinders Centre for Nanoscale Science and Technology, Flinders University , Sturt Road, Bedford Park, Adelaide, SA 5042, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Lewis
authors.affiliation: Flinders Centre for Nanoscale Science and Technology, Flinders University , Sturt Road, Bedford Park, Adelaide, SA 5042, Australia.
authors.forename: Gunther G
authors.identifier: http://orcid.org/0000-0001-5742-3037
authors.initials: GG
authors.lastname: Andersson
authors.affiliation: Future Industries Institute, University of South Australia , Adelaide, SA 5095, Australia.
authors.forename: Mats R
authors.initials: MR
authors.lastname: Andersson
keywords: cathode interface layer; inverted OSCs; morphology; pyridine; work function