title: Molecular weight dependent bimolecular recombination in organic solar cells.
abstract: Charge carrier recombination is studied in operational organic solar cells made from the polymer:fullerene system PCDTBT:PC71BM (poly[N-9''-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]: [6,6]-phenyl-C70-butyric acid methyl ester). A newly developed technique High Intensity Resistance dependent PhotoVoltage is presented for reliably quantifying the bimolecular recombination coefficient independently of variations in experimental conditions, thereby resolving key limitations of previous experimental approaches. Experiments are performed on solar cells of varying thicknesses and varying polymeric molecular weights. It is shown that solar cells made from low molecular weight PCDTBT exhibit Langevin recombination, whereas suppressed (non-Langevin) recombination is found in solar cells made with high molecular weight PCDTBT.
authors.affiliation: College of Science, Technology and Engineering, James Cook University, Townsville 4811, Australia.
authors.forename: Bronson
authors.initials: B
authors.lastname: Philippa
authors.affiliation: Centre for Organic Photonics and Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
authors.forename: Martin
authors.initials: M
authors.lastname: Stolterfoht
authors.affiliation: College of Science, Technology and Engineering, James Cook University, Townsville 4811, Australia.
authors.forename: Ronald D
authors.initials: RD
authors.lastname: White
authors.affiliation: Centre for Organic Photonics and Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
authors.forename: Marrapan
authors.initials: M
authors.lastname: Velusamy
authors.affiliation: Centre for Organic Photonics and Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Burn
authors.affiliation: Centre for Organic Photonics and Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Meredith
authors.affiliation: Centre for Organic Photonics and Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
authors.forename: Almantas
authors.initials: A
authors.lastname: Pivrikas