How to Drive a Flashing Electron Ratchet to Maximize Current

Ofer Kedem, Bryan Lau, Emily A. Weiss

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

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
Pages (from-to)5848-5854
Number of pages7
JournalNano letters
Volume17
Issue number9
DOIs
Publication statusPublished - Sep 13 2017

Keywords

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

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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