Spin Rabi flopping in the photocurrent of a polymer light-emitting diode

McCamey, Dane R.; Seipel, Heather; Paik, Seoyoung; Walter, Manfred J.; Borys, Nicholas J.; Lupton, John M.; Boehme, Christoph

doi:10.1038/nmat2252

Cited by 147 publications

(198 citation statements)

References 51 publications

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“…1). To remove the background, a signal acquired at 320 mT is subtracted from all the data following a similar procedure as reported in [17]. In Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Continuous wave (CW) magnetic resonance techniques were also used as alternative methods to investigate spin effects in organic semiconductors [4,5,[14][15][16]. However there are very few papers on time resolved studies, in spite of the abundance of information that these techniques can provide [17,18]. Moreover most work was performed at low temperature, but it was shown that different phenomena come into play at room temperature where the magnetic resonance signal and organic magneto-resistance change sign [14,19].…”

Section: Introductionmentioning

confidence: 99%

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Pulsed magnetic resonance of Alq3 OLED detected by electroluminescence

Comandè

Ansermet

2013

Synthetic Metals

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The aim of the present work is to investigate the nature of spin dependent processes in an organic light emitting diode based on a ITO/ α-NPD/Alq3 structure. The electroluminescence time response of the sample is monitored while the OLED is exposed to a high power resonant microwave pulse. Measurements are carried out at room temperature. The time scale of the induced transition is found to be independent of the bias voltage. It is shown, by way of a simulation, that this behavior appears inconsistent with models which attribute a change in the electroluminescence to a variation in charge mobility. Spin dependent processes directly related to a change in the rate of charge recombination play therefore a relevant role in Alq 3 light emitting diodes.

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“…1). To remove the background, a signal acquired at 320 mT is subtracted from all the data following a similar procedure as reported in [17]. In Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pulsed magnetic resonance of Alq3 OLED detected by electroluminescence

Comandè

Ansermet

2013

Synthetic Metals

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“…In Fig. 3 we used the parameters inferred for a semiconducting fluorescent polymer [17], implying w d k r .…”

Section: Strong Resonant Drive ω 1 ω Hfmentioning

confidence: 99%

“…According to experiments, this regime is characterized by very close electron-and hole-polaron g factors [10,16], relatively strong hyperfine interaction [11,16,17], relatively slow recombination from the singlet polaron pair state [7,17], relatively slow annihilation of triplet excitons from doublet triplet-polaron state [6,8], relatively long spin coherence times [16,17], weak exchange [18], and weak dipolar interaction between polaron pair or exciton-polaron spins [6,9,18], etc.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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Mkhitaryan, Vagharsh; Danilovic, Dusan; Hippola, Chamika M.; Raikh, M. E.; and Shinar, Joseph, "Comparative analysis of magnetic resonance in the polaron pair recombination and the triplet exciton-polaron quenching models" (2018). Ames Laboratory Accepted Manuscripts. 92. http://lib.dr.iastate.edu/ameslab_manuscripts/92Comparative analysis of magnetic resonance in the polaron pair recombination and the triplet exciton-polaron quenching models AbstractWe 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. 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, show...

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“…[7][8][9] Substantial progress in this direction was made by the pulsed EDMR (pEDMR) experiments. [10][11][12][13][14][15][16] Unlike the continuous wave measurements, these experiments are capable of probing the coherent spin dynamics, and thus provide a closer view on the spin-dependent processes. Importantly, pEDMR (and pODMR) offer the implementation of various spin-echo based spectroscopic techniques in the study of organic semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Polaron spin echo envelope modulations in an organic semiconducting polymer

Mkhitaryan

Dobrovitski

2017

Phys. Rev. B

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Theoretical treatment of the electron spin echo envelope modulation (ESEEM) spectra from polarons in a semiconducting π-conjugated polymer is presented. The contact hyperfine coupling and the dipolar interaction between the polaron and proton spins are found to have distinct contributions in the ESEEM spectra. However, since the two contributions are spaced very closely, and the dipolar contribution is dominant, the detection of the contact hyperfine interaction is difficult. To resolve this problem, a recipe of probing the contact hyperfine and dipolar interactions selectively is proposed, and a method for detecting the polaron contact hyperfine interaction is formulated. The ESEEM decay due to the polaron random hopping is analyzed, and the robustness of the method against this decay is verified. Moreover, this decay is linked to the transport properties of polarons, providing an auxiliary probe for the polaron transport.

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Spin Rabi flopping in the photocurrent of a polymer light-emitting diode

Cited by 147 publications

References 51 publications

Pulsed magnetic resonance of Alq3 OLED detected by electroluminescence

Pulsed magnetic resonance of Alq3 OLED detected by electroluminescence

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

Polaron spin echo envelope modulations in an organic semiconducting polymer

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