Ultrasmall magnetic field-effect and sign reversal in transistors based on donor/acceptor systems
| Autor: | Tobat P. I. Saragi, Thomas Reichert |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Materials science
Magnetoresistance General Physics and Astronomy Electron donor 02 engineering and technology lcsh:Chemical technology 01 natural sciences lcsh:Technology Full Research Paper chemistry.chemical_compound 0103 physical sciences Nanotechnology General Materials Science lcsh:TP1-1185 Electrical and Electronic Engineering Thin film 010306 general physics lcsh:Science chemistry.chemical_classification Bipolaron Condensed matter physics lcsh:T Charge (physics) Electron acceptor 021001 nanoscience & nanotechnology organic transistors lcsh:QC1-999 Magnetic field Nanoscience chemistry Quasiparticle donor/acceptor system lcsh:Q sign reversal 0210 nano-technology ultrasmall magnetic field-effects lcsh:Physics organic magnetoresistance |
| Zdroj: | Beilstein Journal of Nanotechnology Beilstein Journal of Nanotechnology, Vol 8, Iss 1, Pp 1104-1114 (2017) |
| ISSN: | 2190-4286 |
| Popis: | We present magnetoresistive organic field-effect transistors featuring ultrasmall magnetic field-effects as well as a sign reversal. The employed material systems are coevaporated thin films with different compositions consisting of the electron donor 2,2',7,7'-tetrakis-(N,N-di-p-methylphenylamino)-9,9'-spirobifluorene (Spiro-TTB) and the electron acceptor 1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile (HAT-CN). Intermolecular charge transfer between Spiro-TTB and HAT-CN results in a high intrinsic charge carrier density in the coevaporated films. This enhances the probability of bipolaron formation, which is the process responsible for magnetoresistance effects in our system. Thereby even ultrasmall magnetic fields as low as 0.7 mT can influence the resistance of the charge transport channel. Moreover, the magnetoresistance is drastically influenced by the drain voltage, resulting in a sign reversal. An average B0 value of ≈2.1 mT is obtained for all mixing compositions, indicating that only one specific quasiparticle is responsible for the magnetoresistance effects. All magnetoresistance effects can be thoroughly clarified within the framework of the bipolaron model. |
| Databáze: | OpenAIRE |
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