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dc.contributor.authorGuerrero, Antonio
dc.contributor.authorMontcada, Núria F.
dc.contributor.authorAjuria, Jon
dc.contributor.authorEtxebarria, Ikerne
dc.contributor.authorPacios, Roberto
dc.contributor.authorGarcia-Belmonte, Germà
dc.contributor.authorPalomares, Emilio
dc.date.accessioned2014-03-06T08:32:14Z
dc.date.available2014-03-06T08:32:14Z
dc.date.issued2013-08
dc.identifier.citationGUERRERO, Antonio, et al. Charge carrier transport and contact selectivity limit the operation of PTB7-based organic solar cells of varying active layer thickness. Journal of Materials Chemistry A, 2013, 1.39: 12345-12354.ca_CA
dc.identifier.urihttp://hdl.handle.net/10234/85609
dc.description.abstractIn this work we study the different electrical loss pathways occurring during the operation of bulk heterojunction solar cells by using a variety of electrical and optical characterization techniques beyond the current density–voltage curve (J–V): Impedance Spectroscopy (IS), Charge Extraction (CE) and Transient Photovoltage (TPV). Two sets of devices are analyzed: the first is based on the donor polymer P3HT, known to provide efficient cells using thick active layers (i.e. 270 nm), and the recently developed PTB7 which offers maximum efficiencies for devices with thinner layers (i.e. 100 nm). Devices fabricated with P3HT:PC60BM are not limited by transport of carriers and large active layer thickness may be used. Importantly, increasing the active layer thickness does not modify the contact selectivity. This is supported by analysis of the diode curve measured in the dark (similar leakage currents) and by capacitance–voltage measurements (similar fullerene content covering the cathode). Under these conditions the current density curve under illumination is mainly defined by the recombination processes taking place in the bulk of the active layer. In contrast, transport of carriers and contact selectivity are both limiting factors for the PTB7:PC60BM system. In this case, best efficiencies are obtained with a low active layer thickness and a high fullerene ratio. Reduced active layer thickness minimizes undesired electrical resistances related to carrier transport through the bulk of the active layer. High fullerene content enhances the amount of fullerene molecules at the cathode leading to decreased leakage currents. Then, the overall device efficiency will be a combination of the recombination kinetics in the bulk of the active layer, undesired resistance to transport of carriers and leakage current present due to low selectivity of the contact. The use of additives has also been explored which enhances charge generation and extraction. Overall, this work provides a comprehensive guide on how to interpret results obtained from some of the most widely used optoelectronic techniques employed to analyse operating devices.ca_CA
dc.format.extent9 p.ca_CA
dc.format.mimetypeapplication/pdfca_CA
dc.language.isocatca_CA
dc.publisherRoyal Society of Chemistryca_CA
dc.relation.isPartOfJournal of Materials Chemistry A, 2013,1ca_CA
dc.rights© Royal Society of Chemistry 2014ca_CA
dc.subjectsolar cellsca_CA
dc.subjectfullereneca_CA
dc.subjectImpedance Spectroscopyca_CA
dc.subjectCharge Extractionca_CA
dc.subjectTransient Photovoltageca_CA
dc.subjectPolymerca_CA
dc.titleCharge carrier transport and contact selectivity limit the operation of PTB7-based organic solar cells of varying active layer thicknessca_CA
dc.typeinfo:eu-repo/semantics/articleca_CA
dc.identifier.doihttp://dx.doi.org/10.1039/C3TA12358H
dc.rights.accessRightsinfo:eu-repo/semantics/openAccessca_CA


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