Organic electronic ratchets doing work

Abstract

The possibility to extract work from periodic, undirected forces has intrigued scientists for over a century—in particular, the rectification of undirected motion of particles by ratchet potentials, which are periodic but asymmetric functions. Introduced by Smoluchowski and Feynman^1,2 to study the (dis)ability to generate motion from an equilibrium situation, ratchets operate out of equilibrium, where the second law of thermodynamics no longer applies. Although ratchet systems have been both identified in nature^3,4 and used in the laboratory for the directed motion of microscopic objects^5,6,7,8,9, electronic ratchets^10,11,12,13 have been of limited use, as they typically operate at cryogenic temperatures and generate subnanoampere currents and submillivolt voltages^{10,11,12,13,14}. Here, we present organic electronic ratchets that operate up to radio frequencies at room temperature and generate currents and voltages that are orders of magnitude larger. This enables their use as a d.c. power source. We integrated the ratchets into logic circuits, in which they act as the d.c. equivalent of the a.c. transformer, and generate enough power to drive the circuitry. Our findings show that electronic ratchets may be of actual use.