VOLUMETRIC CAPACITANCE IN ORGANIC ELECTROCHEMICAL TRANSISTORS: TECHNIQUES AND PERSPECTIVES

Marcos Luginieski (DR); IFSC-USP; Gregório Faria

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Submission

Paper Title

VOLUMETRIC CAPACITANCE IN ORGANIC ELECTROCHEMICAL TRANSISTORS: TECHNIQUES AND PERSPECTIVES

Authors

Marcos Luginieski (DR); IFSC-USP
Gregório Faria

Modality

Pôster

Subject area

Dispositivos eletrônicos e ópticos (OLED/OFET/OPVs/etc.)

Publishing Date

12/12/2023

Country of Publishing

Brasil

Language of Publishing

Inglês

Paper Page

https://www.even3.com.br/anais/workshop-do-ineo-2023/612798-volumetric-capacitance-in-organic-electrochemical-transistors--techniques-and-perspectives

ISBN

978-65-272-0088-8

Keywords

Organic Electrochemical Transistors, Volumetric capacitance, Electrochemical Impedance Spectroscopy, Transient current

Summary

Organic Electrochemical Transistors (OECTs) operate by mixing the electronic and ionic fluxes through doping or de-doping processes in conducting polymers. While details in the electronic conduction are, somewhat, well addressed in the technical literature, the ionic fluxes and their intricate relationship with the conjugated backbone is yet to be better discussed and modeled. Indeed, the first model able to partially describe output currents in OECT was published in 2007 by Bernards and Malliaras (BM) [1]. In their model, the electronic conduction is based on the same approach used in standard field-effect transistors, while the ionic circuit is modeled by an equivalent circuit of a resistor in series with a capacitor. Late, in 2020, Colucci et. al [2] expanded the BM model, to absorb the figure of merit, volumetric capacitance (C*), being the final output current formula dependent of the product between C* and the electronic mobility (µ) [3]. One of the main techniques used to obtain experimentally the C* is the Electrochemical Impedance Spectroscopy (EIS). There, a capacitor-like structure is used to measure the impedance of the semiconductor film (working electrode), due to a DC bias with a small AC amplitude. Being a two-electrode technique, EIS is not suitable to evaluate capacitances in a three-electrode, transistor structure. Nevertheless, EIS has been extensively used by the OECT community. During the measurement, the drain and source contacts are shorted and grounded together, while the gate contact becomes the working electrode. Therefore, EIS reflects the OECT operation only when VD is zero, which is far from being the most common operation conditions in transistor as a whole. In this condition, the ionic fluxes from the gate into the semiconductor are evenly divided between both drain and source electrodes. However, when operating under a VD bias, the balance of the electric field between the three-electrodes leads to a non-even distribution of ionic fluxes within the channel, completely changing the operation regime. Therefore, one has to be aware that errors might propagate when using C* measured by EIS to reflect the entire regime operation of an OECT. In fact, such EIS limitation can be overcome by measuring the transient response of OECTs under a pulsed gate voltage and a biased VD. This is done by fitting the drain and gate transient curves with the so-called Faria-Duong model (FD) [4]. Here, the FD model allows C* extraction for every combination of VD and VG, overcoming the EIS limitation. It is experimentally proven that EIS can be considered for extracting C* only in the regime where VG >> VD. For regimes where VG ˜ VD or VG << VD only the FD model technique provides manners to evaluate the dependency of C* with VD. By comparing results obtained by EIS and the FD model technique, guidelines for a definitive way of measuring C* in OECTs are discussed and established. Acknowledgments Authors would like to acknowledge the financial support from CAPES and FAPESP. References [1] D. A. Bernards, G. G. Malliaras, Adv Funct Mater 2007, 17, 3538. [2] R. Colucci, H. F. de P. Barbosa, F. Günther, P. Cavassin, G. C. Faria, Flexible and Printed Electronics 2020, 5, 013001. [3] S. Inal, G. G. Malliaras, J. Rivnay, Nat Commun 2017, 8, 1767. [4] G. C. Faria, D. T. Duong, A. Salleo, Org Electron 2017, 45, DOI 10.1016/j.orgel.2017.03.021.

Title of the Event: Workshop do INEO 2023
City of the Event: Nazaré Paulista
Title of the Proceedings of the event: Anais do Workshop INEO 2023
Name of the Publisher: Even3
Means of Dissemination: Meio Digital

How to cite

IFSC-USP, Marcos Luginieski (DR);; FARIA, Gregório. VOLUMETRIC CAPACITANCE IN ORGANIC ELECTROCHEMICAL TRANSISTORS: TECHNIQUES AND PERSPECTIVES.. In: Anais do workshop INEO 2023. Anais...Nazaré Paulista(SP) Hotel Estância Atibainha, 2023. Available in: https//www.even3.com.br/anais/workshop-do-ineo-2023/612798-VOLUMETRIC-CAPACITANCE-IN-ORGANIC-ELECTROCHEMICAL-TRANSISTORS--TECHNIQUES-AND-PERSPECTIVES. Access in: 10/09/2024