Modeling Organic Electrochemical Transistors and Sensors

• Applicants: Professor Dr. Fabio La Mantia; Professor Dr.-Ing. Björn Lüssem
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 524736815

Organic Electrochemical Transistors (OECTs) are heralded as a new paradigm for flexible and wearable electronics. Sensors based on OECTs combine selective recognition of the analyte with an inherent amplification due to the high transconductance of OECTs, resulting in an optimized sensitivity and signal to noise ratio. Organic Electrochemical Transistors are based on mixed organic semiconductors, which are flexible, stretchable, and - in some cases - able to heal if mechanically cut. Most importantly, most mixed organic semiconductors are bio-compatible, which makes them ideal candidates for various healthcare applications. However, much of the progress reached in the past was driven by an heuristic, trial-and-error approach, and efforts to clarify the fundamental working mechanisms of organic electrochemical sensors have not kept pace. This lack in fundamental understanding, and most importantly the lack of an experimentally validated device model is currently slowing further progress in the field as it makes a targeted device optimization impossible and hinders the formulation of synthetic targets for new OECT materials. The proposal addresses this gap. Its aim is to provide an experimentally validated 2D model of organic electrochemical sensors that can be used by the community as a tool for a targeted design of high-performance organic electrochemical sensors. To reach this aim, the proposal pursues the following objectives: i) A numerical framework is implemented to consistently describe multicomponent transport in organic electrochemical transistors and sensors, including a realistic treatment of the chemical reactions providing a selective recognition of different analytes, ii) The model is thoroughly validated by electrical and optical characterization, iii) The model is used to study and describe sensing in OECTs. The project will have an impact on the scientific field of bioelectronics as it will fill various gaps in our understanding of OECTs. It will clarify how the mixed ion and electrons/holes transport observed in OECTs can be modeled, how ions and holes reach a joint equilibrium, and how electron and hole injection at electrodes in the presence of redox reactions can be described. Furthermore, it will clarify, how various sensing mechanisms can be incorporated into current OECT device models, if capacitive or faradaic processes are dominating the sensor response, or how the sensor signal is amplified by the transistor principle of the OECT. Beyond its immediate impact on the bioelectronics field, the project has the potential to move the OECT technology further towards maturity and to turn OECTs into a key technology for wearable electronics used in nursing, healthcare, or the neurosciences.

• DFG Programme: Research Grants
• International Connection: United Kingdom
• Co-Investigator: Dr.-Ing. Ingmar Bösing
• Cooperation Partner: Dr. Scott Keene