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Spin radical enhanced magnetocapacitance effect in intermolecular excited states
Huidong Zang1, Jianguo Wang, Mingxing Li
1Department of Materials Science and Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States.
The Journal of Physical Chemistry. B
|October 23, 2013
Summary
Spin radicals enhance the magnetocapacitance effect in organic polymers. Doping MEH-PPV with spin radicals significantly boosts the magnetocapacitance effect, offering a new method for material enhancement.
Area of Science:
- Organic electronics
- Materials science
- Condensed matter physics
Background:
- The magnetocapacitance effect (MFC) is a phenomenon observed in certain materials where capacitance changes in response to a magnetic field.
- Organic semiconducting polymers like MEH-PPV are promising for electronic applications but often require performance enhancement.
Purpose of the Study:
- To investigate the influence of spin radicals on the magnetocapacitance effect in the polymer MEH-PPV.
- To understand the mechanism behind the observed magnetocapacitance effect and how spin radicals modify it.
Main Methods:
- Fabrication of pristine and spin radical-doped MEH-PPV (6R-BDTSCSB) composite systems.
- Measurement of magnetocapacitance effect under photoexcitation and dark conditions at room temperature.
- Comparative analysis of the effects of spin radicals and photoexcitation intensity on MFC.
Main Results:
- Photoexcitation induces a significant positive MFC in pristine MEH-PPV.
- Low doping of spin radicals in MEH-PPV leads to increased MFC amplitude and line-shape narrowing under illumination.
- No MFC signal was observed in the dark for either pristine or doped samples.
- The effects of spin radicals mimic those of increased photoexcitation intensity.
Conclusions:
- The MFC in MEH-PPV originates from intermolecular excited states (electron-hole pairs) generated by photoexcitation.
- Doped spin radicals interact with these intermolecular excited states, influencing spin-exchange interactions and enhancing the MFC.
- Dispersing spin radicals is an effective strategy to improve the magnetocapacitance effect in organic semiconductors.
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