Salts as Additives: A Route to Improve Performance and Stability of n-Type Organic Electrochemical Transistors
byDavid
Ohayon, Lucas
Q. Flagg, Andrea
Giugni, Shofarul
Wustoni, Ruipeng
Li, Tania
C. Hidalgo Castillo, Iain
McCulloch, Lee
J. Richter, Sahika
Inal
Year:2022
Abstract
Organic electrochemical transistors (OECTs) are
becoming increasingly ubiquitous in various applications at the interface with
biological systems. However, their widespread use is hampered by the scarcity
of electron-conducting (n-type) backbones and the poor performance and
stability of the existing n-OECTs. Here, we introduce organic salts as a
solution additive to improve the transduction capability, shelf life, and
operational stability of n-OECTs. We demonstrate that the salt-cast devices
present a 10-fold increase in transconductance and achieve at least one
year-long stability, while the pristine devices degrade within four months of
storage. The salt-added films show improved backbone planarity and greater
charge delocalization, leading to higher electronic charge carrier mobility.
These films show a distinctly porous morphology where the interconnectivity is
affected by the salt type, responsible for OECT speed. The salt-based films
display limited changes in morphology and show lower water uptake upon
electrochemical doping, a possible reason for the improved device cycling
stability. Our work provides a new and easy route to improve n-type OECT
performance and stability, which can be adapted for other electrochemical
devices with n-type films operating at the aqueous electrolyte interface.