A Light-Responsive Organic Electron Flashing Ratchet

Scientific Achievement

We have fabricated a room-temperature flashing electron ratchet (only the second such device to ever appear in the literature) from a blend of conjugated organic materials; upon the application of a shaped, oscillating gate potential, our devices not only produce a source-drain current in the absence of a source-drain bias, but also produce power.

Significance and Impact

This device can be driven by energy input in the form of a sine wave (an unbiased waveform); this result introduces the possibility of using natural oscillation sources (e.g., electromagnetic radiation) to drive ratchets, an important development toward their application in energy conversion.

Top: Design of the flashing organic electron ratchet device. Bottom: Plots of current vs. source-drain voltage for a flashing electron ratchet device with (“532 nm”) and without (“dark”) illumination, and with (“Ratchet”) and without (“Control”) the flashing potential applied; the device only produces a short-circuit current Isc and an open-circuit voltage Voc with the flashing potential on. In the lower right quadrant (shaded), the ratchet is doing work.

Research Details

  • A series of asymmetric Pt “finger electrodes” apply an oscillating electric field to the organic transport layer; the current is measured between Ag source and drain electrodes held at zero bias.

Work performed at Northwestern University