Molecular weight dependent bimolecular recombination in organic solar cells
Journal Publication ResearchOnline@JCUAbstract
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.
Journal
Journal of Chemical Physics
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Volume
141
ISBN/ISSN
1089-7690
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Pages Count
8
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Publisher
American Institute of Physics
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EISSN
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DOI
10.1063/1.4891369