Inversion of Magnetoresistance in Organic Semiconductors

Bergeson, Jeremy D.; Prigodin, V. N.; Lincoln, Derek M.; Epstein, Arthur J.

doi:10.1103/physrevlett.100.067201

Cited by 167 publications

(119 citation statements)

References 24 publications

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“…Additionally, contemporary OMAR models have not been able to explain the positive LFE and HFE in the MC with a single mechanism. With respect to the origin of the MC(V ) trend, multiple suggestions have been made, 6,28,33,34 but none have succeeded in giving a full quantitative description. Therefore, we have constructed a quantitative trion model with all previous reasoning in mind.…”

Section: Trion Modelmentioning

confidence: 99%

Traps and trions as origin of magnetoresistance in organic semiconductors

et al. 2013

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The large effect of a small magnetic field on the current, magnetoconductance (MC), in organic semiconductors-so-called organic magnetoresistance-has puzzled the field of organic spintronics during the last decade. Although the microscopic mechanisms regarding spin mixing are well understood by now, it is still unknown which pairs of spin carrying particles are influencing the current in such a drastic manner. Here, a model for the MC is presented based on the spin selective formation of metastable trions from triplet exciton-polaron pairs. Additionally, the magnetic-field and voltage dependence of the MC are experimentally investigated in materials showing large effects. Using a combination of analytical and numerical calculations, it is shown that the MC is perfectly described by a process in which trions are created at polaron trap sites.

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Section: Trion Modelmentioning

confidence: 99%

Traps and trions as origin of magnetoresistance in organic semiconductors

et al. 2013

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“…19 Hu et al 14 observed the negative MC response when the triplet exciton-charge reaction in the active layer dominates the generation of the current in a charge-unbalanced device, because of the reduced interaction between triplet excitons with the excess charges by an external magnetic field. 14 Modulating the dissociation of the excited states (positive MC component) and triplet exciton-charge reaction (negative MC component) by the applied magnetic field, changes the sign of MC curves.…”

Section: Introductionmentioning

confidence: 99%

“…a Author to whom correspondence should be addressed; electronic mail: guotf@mail.ncku.edu.tw The sign of MC curves can be either positive or negative by varying the device structures, 14,15 active materials, 16 and experimental conditions, such as illumination, 17 external bias voltage, 18,19 and temperature. 19 Hu et al 14 observed the negative MC response when the triplet exciton-charge reaction in the active layer dominates the generation of the current in a charge-unbalanced device, because of the reduced interaction between triplet excitons with the excess charges by an external magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Modulating the line shape of magnetoconductance by varying the charge injection in polymer light-emitting diodes

et al. 2018

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We fabricate the phenyl-substituted poly(p-phenylene vinylene) copolymer (super yellow, SY-PPV)-based polymer light-emitting diodes (PLEDs) with different device architectures to modulate the injection of opposite charge carriers and investigate the corresponding magnetoconductance (MC) responses. At the first glance, we find that all PLEDs exhibit the positive MC responses. By applying the mathematical analysis to fit the curves with two empirical equations of a non-Lorentzian and a Lorentzian function, we are able to extract the hidden negative MC component from the positive MC curve. We attribute the growth of the negative MC component to the reduced interaction of the triplet excitons with charges to generate the free charge carriers as modulated by the applied magnetic field, known as the triplet exciton-charge reaction, by analyzing MC responses for PLEDs of the charge-unbalanced and hole-blocking device configurations. The negative MC component causes the broadening of the line shape in MC curves.

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“…As a result, magnetically changing charge density becomes a practical method to generate MC, leading to density-based MC in fluorescent organic semiconductors. 1,[13][14][15] More specifically, there are two channels, namely, dissociation and charge-reaction, to generate density-based MC. In dissociation channel, an applied magnetic field can increase the singlet ratio in polaron-pair states through intersystem crossing.…”

mentioning

confidence: 99%

“…7-12) or density-based MC. 1,[13][14][15] In mobility-based MC, organic semiconductors need to have spin-spin interaction between charge carriers during transport. Applying magnetic field can disturb this spin-spin interaction through magnetic scattering and, consequently, modifies charge mobilities, generating mobility-based MC.…”

mentioning

confidence: 99%

Changing inter-molecular spin-orbital coupling for generating magnetic field effects in phosphorescent organic semiconductors

Yan

Shao

Graeff

et al. 2012

Applied Physics Letters

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Phosphorescent organic semiconductors normally show negligible magnetic field effects in electronic and optic responses. These phenomena have been generally attributed to strong spin-orbital coupling which can dominate internal spin-dephasing process as compared with applied magnetic field. This paper reports both positive and negative magnetocurrents from phosphorescent organic semiconductors through dissociation and charge-reaction channels when the intermolecular spin-orbital coupling is changed based on materials mixing. Our experimental results indicate that inter-molecular spin-orbital coupling is essentially responsible for the generation of magnetic field effects in phosphorescent organic semiconductors.

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Inversion of Magnetoresistance in Organic Semiconductors

Cited by 167 publications

References 24 publications

Traps and trions as origin of magnetoresistance in organic semiconductors

Traps and trions as origin of magnetoresistance in organic semiconductors

Modulating the line shape of magnetoconductance by varying the charge injection in polymer light-emitting diodes

Changing inter-molecular spin-orbital coupling for generating magnetic field effects in phosphorescent organic semiconductors

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