How to Drive a Flashing Electron Ratchet to Maximize Current

Ofer Kedem, Bryan Lau, Emily A. Weiss*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Biological systems utilize a combination of asymmetry, noise, and chemical energy to produce motion in the highly damped environment of the cell with molecular motors, many of which are "ratchets", nonequilibrium devices for producing directed transport using nondirectional perturbations without a net bias. The underlying ratchet principle has been implemented in man-made micro- and nanodevices to transport charged particles by oscillating an electric potential with repeating asymmetric features. In this experimental study, the ratcheting of electrons in an organic semiconductor is optimized by tuning the temporal modulation of the oscillating potential, applied using nanostructured electrodes. An analytical model of steady-state carrier dynamics is used to determine that symmetry-breaking motion of carriers through the thickness of the polymer layer enables even temporally unbiased waveforms (e.g., sine) to produce current, an advance that could allow the future use of electromagnetic radiation to power ratchets. The analysis maps the optimal operating frequency of the ratchet to the mobility of the transport layer and the spatial periodicity of the potential, and relates the dependence on the temporal waveform to the dielectric characteristics and thickness of the layer.

Original languageEnglish (US)
Pages (from-to)5848-5854
Number of pages7
JournalNano letters
Issue number9
StatePublished - Sep 13 2017


  • Brownian motor
  • Ratchet
  • charge transport
  • nonequilibrium
  • organic semiconductor
  • temporal modulation

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering


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