Electrochemical reduction and oxidation of PEDOT:PSS are used to modulate the channel current in organic electrochemical transistors (OECTs). In addition to changing PEDOT conductivity over more than 4 orders of magnitude, these redox reactions cause a shift in the PEDOT:PSS absorption spectrum. In this work we have used this shift in the absorption spectrum to make spatially and temporally resolved measurements of the redox state of PEDOT:PSS. By applying these measurements to the PEDOT:PSS in an OECT channel, we have shown that the redox state of the PEDOT:PSS is not constant along the channel during transistor operation. Furthermore, we have shown that the time constant of the optical transition is significantly larger near the transistor source than it is near the transistor drain. These results are not considered in existing models of the OECT transient response, and they may lead to a better understanding of geometry-performance relationships in OECTs.

Date Published: 7 October 2014
PDF: 8 pages
Proc. SPIE 9185, Organic Field-Effect Transistors XIII; and Organic Semiconductors in Sensors and Bioelectronics VII, 91851X (7 October 2014); doi: 10.1117/12.2063564

Published in SPIE Proceedings Vol. 9185:
Organic Field-Effect Transistors XIII; and Organic Semiconductors in Sensors and Bioelectronics VII
Zhenan Bao; Ruth Shinar; Ioannis Kymissis; Iain McCulloch, Editor(s)