Publication Type:Journal Article
Source:Nature Nanotechnology, Nature Publishing Group, Volume 5, Number 2, p.143-147 (2010)
Keywords:Article, bismuth compounds, Charge separations, Different mechanisms, Domain walls, electric field, Electric fields, electric potential, Electric-field control, Electron hole pairs, Electronics, Electrostatic potentials, Energy conversion, Energy gap, Ferroelectric domains, Ferroelectric materials, ferroelectricity, iron compounds, light absorption, nanomaterial, Optoelectronic devices, photovoltaic device, Photovoltaic devices, Photovoltaic effects, priority journal, semiconductor, Semiconductor devices, Semiconductor electronics, solid state
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 1-2nm 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 BiFeO 3. 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. © 2010 Macmillan Publishers Limited. All rights reserved.
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