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Trap healing and ultralow-noise Hall effect at the surface of organic semiconductors

Nature Materials volume 12, pages 1125–1129 (2013)Cite this article

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Abstract

Fundamental studies of intrinsic charge transport properties of organic semiconductors are often hindered by charge traps associated with static disorder present even in optimized single-crystal devices. Here, we report a method of surface functionalization using an inert non-conjugated polymer, perfluoropolyether (PFPE), deposited at the surface of organic molecular crystals, which results in accumulation of mobile holes and a ‘trap healing’ effect at the crystal/PFPE interface. As a consequence, a remarkable ultralow-noise, trp-free conduction regime characterized by intrinsic mobility and transport anisotropy emerges in organic single crystals, and Hall effect measurements with an unprecedented signal-to-noise ratio are demonstrated. This general method to convert trap-dominated organic semiconductors to intrinsic systems may enable the determination of intrinsic transport parameters with high accuracy and make Hall effect measurements in molecular crystals ubiquitous.

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Figure 1: Surface charge accumulation in rubrene single crystals with PFPE polymer.
Figure 2: Anisotropic surface conductivity induced by PFPE in molecular crystals.
Figure 3: Trap-healing effect of PFPE revealed in FET measurements.
Figure 4: Hall effect at the surface of rubrene functionalized with PFPE.

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Acknowledgements

This work has been financially supported by a DOE BES award under grant no. DE-SC0005464 (ER46763) and NSF-DMR-0843985. We are very grateful to H. Lee and A. L. Briseno for their help with density functional theory calculations. We are also very grateful to E. A. Chandross, E. Galoppini and Y. Cao for useful discussions and to S-Y. Wang for her help with organic single-crystal growth.

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  1. B. Lee and Y. Chen: These authors contributed equally to this work

Authors and Affiliations

  1. Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA

    B. Lee, Y. Chen, D. Fu, H. T. Yi, K. Czelen, H. Najafov & V. Podzorov

  2. Institute for Advanced Materials and Devices for Nanotechnology (IAMDN), Rutgers University, Piscataway, New Jersey 08854, USA

    V. Podzorov

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  1. B. Lee
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Contributions

B.L., Y.C., D.F., H.T.Y., K.C. and H.N. performed crystal growth, device fabrication and measurements. B.L., Y.C. and V.P. designed the experiments and analysed data. V.P. guided the work. Y.C. and V.P. wrote the manuscript with input from all authors.

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Correspondence to V. Podzorov.

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Lee, B., Chen, Y., Fu, D. et al. Trap healing and ultralow-noise Hall effect at the surface of organic semiconductors. Nature Mater 12, 1125–1129 (2013). https://doi.org/10.1038/nmat3781

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