Organic Magnetoresistance and Spin Diffusion in Organic Semiconductor Thin‐Film Devices

Wohlgenannt, M.

doi:10.1002/9783527654949.ch9

Cited by 4 publications

(5 citation statements)

References 58 publications

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“…The OMAR response of the Au/BDTT thin film/Au device showed a distinct non-Lorentzian behavior with a relatively larger MR ratio and much wider line width compared to that of the single-crystal one for a wide range of current and temperature (Figure 4b,c). Unlike conventional non-Lorentz fitted OMAR curves, which show a clear down-curving trend when the magnetic field increases (those shapes generally remain the same with various current and temperature, from a few K up to room temperature), 4 the behavior of the thin-filmbased OMAR exhibited a strong dependence on the measurement conditions. We speculate that this abnormal phenomenon is related to the trap-state-induced regulation mechanism in the pure bipolaron model.…”

Section: Resultsmentioning

confidence: 75%

“…The singlecrystal devices show a small B sat of ∼10 mT, and MR curves are in agreement with the saturated Lorentz model (Figure 3b), which are much different from noncrystal materials reported with a saturation magnetic field B sat generally above 50 mT and even with an unsaturated line shape. 4 Considering the non-Lorentzian model is the most commonly used, OMAR curves are also fitted with the non-Lorentz model for comparison (Figure 3c, Table S1). The MR of BDTT single-crystal device decreases slightly as the current increases at a constant temperature (Figure 3b), while as the temperature increases, the MR curves are slightly broadened and the value of MR declines (Figure 3c).…”

Section: Resultsmentioning

confidence: 99%

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Organic Single-Crystal Spintronics: Magnetoresistance Devices with High Magnetic-Field Sensitivity

Ding

Tian

et al. 2019

ACS Nano

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Organic spintronics is a new emerging field that deals with the spin-related phenomena of organic materials under the influence of a magnetic field. However, there remain some challenges in organic spintronics including (i) low conductivity and massive disorders of organic thin films blocking the way to controllable spin transport, (ii) relatively low magnetic-field sensitivity of organic magnetoresistance (OMAR) devices with tangled working mechanisms and short of methods for sensitivity improvement. Here, we report the realization of OMAR devices based on organic single crystals. The lesser amount of impurities and defects in crystals guarantees a reduction in spin and charge scatterings, so that the OMAR devices exhibit both a small Lorentz function fitting parameter B 0 of 2.3 mT and a non-Lorentz function fitting parameter B 1 of 0.86 mT in the strictly limited bipolaron model. Moreover, we demonstrate the effect of aggregation and intrinsic trap states, pointing out a way for the improvement of the sensitivity.

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Section: Resultsmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Organic Single-Crystal Spintronics: Magnetoresistance Devices with High Magnetic-Field Sensitivity

Ding

Tian

et al. 2019

ACS Nano

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“…Molecular spintronics, which combines the potential of spintronics and organic electronics is a promising alternative to conventional spintronics with inorganic materials [193]. The mixing of the triplet and singlet states as a result of the hyperfine field (of the hydrogen atoms) in organic semiconductors manifests itself as a large magnetoresistance effect [194,195]. Presumably, if electrical leads could be easily attached to conjugated polymers and molecules in a DAC for magneto-electric measurements, high pressure could serve as a powerful tuning parameter to study spin transport in organic spintronics.…”

Section: Discussionmentioning

confidence: 99%

Blue emitting organic semiconductors under high pressure: status and outlook

Knaapila¹,

Guha²

2016

Rep. Prog. Phys.

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This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure and intermolecular self-organization that typically determine transport and optical emission in π-conjugated oligomers and polymers. In this context, hydrostatic pressure through diamond anvil cells has proven to be an elegant tool to control structure and interactions without chemical intervention. This has been highlighted by high pressure optical spectroscopy whilst analogous x-ray diffraction experiments remain less frequent. By focusing on a class of blue-emitting π-conjugated polymers, polyfluorenes, this article reviews optical spectroscopic studies under hydrostatic pressure, addressing the impact of molecular and intermolecular interactions on optical excitations, electron-phonon interaction, and changes in backbone conformations. This picture is connected to the optical high pressure studies of other π-conjugated systems and emerging x-ray scattering experiments from polyfluorenes which provides a structure-property map of pressure-driven intra- and interchain interactions. Key obstacles to obtain further advances are identified and experimental methods to resolve them are suggested.

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“…As a result, the electron spin becomes a robust quantity within the OS (namely, it has long spin diffusion length and coherence time). Electron spin diffusion lengths in the range of 5-100 nm have been demonstrated (depending on the experiment, film morphology, temperature); [10][11][12][13] moreover, even longer ~1 μm spin diffusion length have been measured in doped OS. [14] Electron spin coherence times last as long as ~1 μsec.…”

Section: General Overviewmentioning

confidence: 98%

Magnetic Field Effects of Charge Transfer Excitons in Organic Semiconductor Devices

Nikiforov

Ehrenfreund

2021

Israel Journal of Chemistry

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The topic of this review is the effect of magnetic field on photo‐current (PC) in organic semiconductor devices. Magnetic field modifies the fraction of the singlet/triplet population in the charge transfer excitons (CTE) whose lifetime is spin configuration dependent yielding magneto‐PC (MPC). We review MPC in the framework of the polaron pair model and emphasize the effect of CTE lifetime on MPC. In addition to a detailed calculation of the MPC response we find a range of physical parameters in which the response follows a simple ′fit function′. For example, a sum of wide and narrow Lorentzian functions, MPC(B)=cwB2/(B2+bw2)+cnB2/(B2+bn2), in the case of hyperfine interaction; or a Voigt profile V=L*G, where the sign * stands for the convolution operation between a Lorentzian (L) and a Gaussian (G) functions, in the case of thermal spin polarization. We provide expressions for the fit parameters in terms of physical parameters.

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Organic Magnetoresistance and Spin Diffusion in Organic Semiconductor Thin‐Film Devices

Cited by 4 publications

References 58 publications

Organic Single-Crystal Spintronics: Magnetoresistance Devices with High Magnetic-Field Sensitivity

Organic Single-Crystal Spintronics: Magnetoresistance Devices with High Magnetic-Field Sensitivity

Blue emitting organic semiconductors under high pressure: status and outlook

Magnetic Field Effects of Charge Transfer Excitons in Organic Semiconductor Devices

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