Comparative analysis of magnetic resonance in the polaron pair recombination and the triplet exciton-polaron quenching models

dc.contributor.author Mkhitaryan, Vagharsh
dc.contributor.author Danilovic, Dusan
dc.contributor.author Hippola, Chamika
dc.contributor.author Raikh, M.
dc.contributor.author Shinar, Joseph
dc.contributor.department Ames Laboratory
dc.contributor.department Ames National Laboratory
dc.date 2018-02-19T07:37:42.000
dc.date.accessioned 2020-06-29T23:24:59Z
dc.date.available 2020-06-29T23:24:59Z
dc.date.issued 2018-01-03
dc.description.abstract <p>We present a comparative theoretical study of magnetic resonance within the polaron pair recombination (PPR) and the triplet exciton-polaron quenching (TPQ) models. Both models have been invoked to interpret the photoluminescence detected magnetic resonance (PLDMR) results in π -conjugated materials and devices. We show that resonance line shapes calculated within the two models differ dramatically in several regards. First, in the PPR model, the line shape exhibits unusual behavior upon increasing the microwave power: it evolves from fully positive at weak power to fully negative at strong power. In contrast, in the TPQ model, the PLDMR is completely positive, showing a monotonic saturation. Second, the two models predict different dependencies of the resonance signal on the photoexcitation power, P L . At low P L , the resonance amplitude Δ I / I is ∝ P L within the PPR model, while it is ∝ P 2 L crossing over to P 3 L within the TPQ model. On the physical level, the differences stem from different underlying spin dynamics. Most prominently, a negative resonance within the PPR model has its origin in the microwave-induced spin-Dicke effect, leading to the resonant quenching of photoluminescence. The spin-Dicke effect results from the spin-selective recombination, leading to a highly correlated precession of the on-resonance pair partners under the strong microwave power. This effect is not relevant for TPQ mechanism, where the strong zero-field splitting renders the majority of triplets off resonance. On the technical level, the analytical evaluation of the line shapes for the two models is enabled by the fact that these shapes can be expressed via the eigenvalues of a complex Hamiltonian. This bypasses the necessity of solving the much larger complex linear system of the stochastic Liouville equations. Our findings pave the way towards a reliable discrimination between the two mechanisms via cw PLDMR.</p>
dc.identifier archive/lib.dr.iastate.edu/ameslab_manuscripts/92/
dc.identifier.articleid 1097
dc.identifier.contextkey 11384380
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath ameslab_manuscripts/92
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/7629
dc.language.iso en
dc.relation.ispartofseries IS-J 9557
dc.source.bitstream archive/lib.dr.iastate.edu/ameslab_manuscripts/92/IS_J_9557.pdf|||Sat Jan 15 02:29:52 UTC 2022
dc.source.uri 10.1103/PhysRevB.97.035402
dc.subject.disciplines Condensed Matter Physics
dc.title Comparative analysis of magnetic resonance in the polaron pair recombination and the triplet exciton-polaron quenching models
dc.type article
dc.type.genre article
dspace.entity.type Publication
relation.isOrgUnitOfPublication 25913818-6714-4be5-89a6-f70c8facdf7e
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