OECT Device Physics
Organic electrochemical transistors (OECTs) are thin-film transistors with an organic semiconductor channel between source and drain electrodes. OECTs are structured much like organic field-effect transistors (OFETs) with the distinction that OECTs have an electrolyte layer between the channel and the gate electrode instead of a standard dielectric. We develop and validate models that provide quantitative explanations for previously unexplained characteristics. Ultimately, these models inform the design of OECT sensors and circuits, and they provide a way to measure the material properties of the polymer semiconductors used in OECTs, thus aiding the development of new polymers for performance optimization in different applications.
The team
- Megan Renny (PhD Student)
- Natalie Alvarado (Undergraduate Student)
- Brenna Curvey (Undergraduate Student)
Learn more
- J. T. Friedlein, J. Rivnay, D. H. Dunlap, I McCulloch, S. E. Shaheen, R. R. McLeod, George G. Malliaras, “Influence of disorder on transfer characteristics of organic electrochemical transistors,” Applied Physics Letters 111, 023301 (2017)
- J. T. Friedlein, M. J. Donahue, S. E. Shaheen, G. G. Malliaras, and R. R. McLeod, “Microsecond Response in Organic Electrochemical Transistors: Exceeding the Intrinsic Speed Limit,” Advanced Materials 28, 8398–8404, 2016.
- J. T. Friedlein, S. E. Shaheen, G. G. Malliaras, R. R. McLeod, Optical measurements revealing non-uniform hole mobility in organic electrochemical transistors, Advanced Electronic Materials 2015, pp. 1500189 (9 pages), 2015.
- Jacob Friedlein, Doctor of Philosophy in Electrical Engineering, Device physics and material science of organic electrochemical transistors, University of Colorado, 2017.
This work has been generously funded by
Sample results
In an OECT, mobile ions are pushed from the electrolyte into the polymer semiconductor by a gate voltage. These ions dope (or de-dope) the semiconductor, changing its conductivity. Unlike OFETs, ionic and electronic charge transport occurs throughout the volume of the condutive polymer channel.
Change in current through the channel (top) in response to a voltage step on the gain (bottom) compared to our model. We extended the seminal work of Bernards and Malliaras, particularly by including the unusually high ionic displacement current.
The change in gate current in response to a change in gate voltage, called the transconductance, is very high in OECTs and exploited for high sensitivity. We have explained the variation of transconductance with gate voltage by incorporating the impact of disorder in the semiconductor channel.