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Transistor functions based on electrochemical rectification

Researchers of the State Key Lab of Electroanalytical Chemistry, Chinese Academy of Sciences in Changchun, and the Peter Grünberg Institute, PGI-8, Forschungszentrum Jülich, have developed together a novel chip-based molecular transistor concept, which is based on an electrochemical redox reaction. The unidirectional current recorded at a chemically modified collector electrode can be tuned by the potential applied to an independent generator electrode, which allows switching of the output current and information encoding.



Transistor functions based on electrochemical rectification

By Yaqing Liu, Bernhard Wolfrum, Martin Hüske, Andreas Offenhäusser, Erkang Wang, Dirk Mayer

Published: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION  52,  (2013) 4029-4032 

DOI: 10.1002/anie.201207778  

Transistor functions based on electrochemical rectification Scheme of the molecular redox transistor which is based on a mircostructured interdigitated array electrode pair. One of the interdigitated electrodes (collector electrode) is modified by a monolayer of redox active molecules which act as redox mediator for the exchange of charges between electrode and redox probes in solution.The second electrode (generator electrode) remains unmodified.



Electronic elements built from organic semiconductors such as molecular transistors have significant potential for technical innovations and mass use due to their flexible mechanical properties, cost effective processability and tuneable electrical properties. In this work, a novel chip-based molecular transistor concept is present, which is based on charge transfer processes across a monolayer of molecules, perpendicular to the sample surface plane. Therefore, redox active molecules are adsorbed to a collector electrode (CE) acting as electron-transfer mediators. A two-step charge transfer between solid interdigitated array electrodes (IDA), charge transfer mediator, and liquid-phase redox probe yields a unidirectional current response. An adsorbate-free generator electrode (GE) can be used to modulate the unidirectional currents, resulting in a transistor-like behavior. The device can perform transistor-like functions with opposite current directions depending on kind and concentration of redox inputs used. The electrochemical transistor-like system exhibits high current outputs at a low-voltage operation, high on/off switching current ratios and is operated as a 24-bit code generator.

The open configuration and the dependence of the output signal on external stimuli make this setup interesting for sensor applications. The readout response is furthermore affected if several input signals are mixed together to realized logic gates. Merging the concept of redox based transistor functions with chemical logic gates provides a platform to directly link the emerging field of chemical computing with common strategies of information processing. Moreover, if chemical processes involving recognition reactions are integrated into the system, devices can be envisioned that internally process obtained sensoric information.