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dc.contributor.authorGehrig, Dominik W.
dc.contributor.authorHoward, Ian A.
dc.contributor.authorLaquai, Frédéric
dc.date.accessioned2015-05-25T08:12:26Z
dc.date.available2015-05-25T08:12:26Z
dc.date.issued2015-06-05
dc.identifier.citationCharge Carrier Generation Followed by Triplet State Formation, Annihilation, and Carrier Recreation in PBDTTT-C:PC 60 BM Photovoltaic Blends 2015:150522140657008 The Journal of Physical Chemistry C
dc.identifier.issn1932-7447
dc.identifier.issn1932-7455
dc.identifier.doi10.1021/acs.jpcc.5b03467
dc.identifier.urihttp://hdl.handle.net/10754/555636
dc.description.abstractTriplet state formation after photoexcitation of low-bandgap polymer:fullerene blends has recently been demonstrated, however, the precise mechanism and its impact on solar cell performance is still under debate. Here, we study exciton dissociation, charge carrier generation and triplet state formation in low-bandgap polymer PBDTTT-C:PC60BM bulk heterojunction photovoltaic blends by a combination of fs-µs broadband Vis-NIR transient absorption (TA) pump-probe spectroscopy and multivariate curve resolution (MCR) data analysis. We found sub-ps exciton dissociation and charge generation followed by sub-ns triplet state creation. The carrier dynamics and triplet state dynamics exhibited a very pronounced intensity dependence indicating non-geminate recombination of free carriers is the origin of triplet formation in these blends. Triplets were found to be the dominant state present on the nanosecond timescale. Surprisingly, the carrier population increased again on the ns-µs timescale. We attribute this to triplet-triplet annihilation and the formation of higher energy excited states that subsequently underwent charge transfer. This unique dip and recovery of the charge population is a clear indication that triplets are formed by non-geminate recombination, as such a kinetic is incompatible with a monomolecular triplet state formation process.
dc.publisherAmerican Chemical Society (ACS)
dc.relation.urlhttp://pubs.acs.org/doi/abs/10.1021/acs.jpcc.5b03467
dc.rightsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.5b03467.
dc.subjectcharge generation
dc.subjectlow-bandgap polymers,
dc.subjectmultivariate curve resolution
dc.subjectorganic solar cells
dc.subjecttransient absorption spectroscopy
dc.subjecttriplet states
dc.titleCharge Carrier Generation Followed by Triplet State Formation, Annihilation, and Carrier Recreation in PBDTTT-C:PC 60 BM Photovoltaic Blends
dc.typeArticle
dc.contributor.departmentKAUST Solar Center (KSC)
dc.contributor.departmentMaterial Science and Engineering Program
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.identifier.journalThe Journal of Physical Chemistry C
dc.eprint.versionPost-print
dc.contributor.institutionMax Planck Research Group for Organic Optoelectronics, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
kaust.personLaquai, Frederic
refterms.dateFOA2016-05-22T00:00:00Z
dc.date.published-online2015-06-05
dc.date.published-print2015-06-18


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