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.