Article abstract


Nature Nanotechnology 5, 143 - 147 (2010)
Published online: 10 January 2010 | doi:10.1038/nnano.2009.451

Subject Categories: Nanomaterials | Photonic structures and devices

Above-bandgap voltages from ferroelectric photovoltaic devices

S. Y. Yang1, J. Seidel2,3, S. J. Byrnes2,3, P. Shafer1, C.-H. Yang3, M. D. Rossell4, P. Yu3, Y.-H. Chu5, J. F. Scott6, J. W. Ager, III2, L. W. Martin2 & R. Ramesh1,2,3


In conventional solid-state photovoltaics, electron–hole pairs are created by light absorption in a semiconductor and separated by the electric field spaning a micrometre-thick depletion region. The maximum voltage these devices can produce is equal to the semiconductor electronic bandgap. Here, we report the discovery of a fundamentally different mechanism for photovoltaic charge separation, which operates over a distance of 1–2 nm and produces voltages that are significantly higher than the bandgap. The separation happens at previously unobserved nanoscale steps of the electrostatic potential that naturally occur at ferroelectric domain walls in the complex oxide BiFeO3. Electric-field control over domain structure allows the photovoltaic effect to be reversed in polarity or turned off. This new degree of control, and the high voltages produced, may find application in optoelectronic devices.

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  1. Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California 94720, USA
  2. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  3. Department of Physics, University of California, Berkeley, California 94720, USA
  4. National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  5. Department of Materials Science and Engineering, National Chiao Tung University, HsinChu, Taiwan 30010
  6. Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK

Correspondence to: S. Y. Yang1 e-mail: syyang@berkeley.edu



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