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Solution-processed organic spin–charge converter

Abstract

Conjugated polymers and small organic molecules are enabling new, flexible, large-area, low-cost optoelectronic devices, such as organic light-emitting diodes, transistors and solar cells1. Owing to their exceptionally long spin lifetimes, these carbon-based materials could also have an important impact on spintronics2,3,4,5, where carrier spins play a key role in transmitting, processing and storing information6. However, to exploit this potential, a method for direct conversion of spin information into an electric signal is indispensable. Here we show that a pure spin current can be produced in a solution-processed conducting polymer by pumping spins through a ferromagnetic resonance in an adjacent magnetic insulator, and that this generates an electric voltage across the polymer film. We demonstrate that the experimental characteristics of the generated voltage are consistent with it being generated through an inverse spin Hall effect in the conducting polymer. In contrast with inorganic materials, the conducting polymer exhibits coexistence of high spin-current to charge-current conversion efficiency and long spin lifetimes. Our discovery opens a route for a new generation of molecular-structure-engineered spintronic devices, which could lead to important advances in plastic spintronics.

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Figure 1: Spin–charge conversion in organic material.
Figure 2: Observation of spin–charge current conversion in PEDOT:PSS.
Figure 3: Microwave frequency dependence of electric voltage.

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Acknowledgements

This work was supported by the Cabinet Office, Government of Japan through its Funding Program for Next Generation World-Leading Researchers, the Asahi Glass Foundation and the Engineering and Physical Sciences Research Council (EPSRC). We thank J. Wunderlich of the Hitachi Cambridge Laboratory for stimulating discussions, Y. Vaynzof for performing and analysing the XPS measurements, Z. Qiu for preparing samples, and T. Tashiro for the AFM measurements.

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K.A. and S.W. conceived and designed the experiments, and collected data on the ISHE. K.A. performed analysis of the data, developed the explanation and wrote the manuscript. S.W. and S.M. fabricated devices and performed the physical characterization. S.M. and S.W. wrote the Supplementary Information. E.S. and H.S. supervised this work. All authors discussed results and reviewed the manuscript.

Corresponding author

Correspondence to Kazuya Ando.

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The authors declare no competing financial interests.

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Ando, K., Watanabe, S., Mooser, S. et al. Solution-processed organic spin–charge converter. Nature Mater 12, 622–627 (2013). https://doi.org/10.1038/nmat3634

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