The organic electrochemical transistor (OECT) is an exciting device at the forefront of bioelectronics, with applications ranging from biosensors, electrophysiological monitoring, circuits, etc.

OECT operation and performance rely on the properties of its core components – a mixed ionic/electronic conductor in contact with an electrolyte – and on the form factor that is imparted during device fabrication.¹ While tremendous efforts have been done to improve device performance, strategies that combine efficient operation and sustainable design are still lacking. Most organic mixed ionic/electronic conductors are synthesized using multiple steps involving toxic precursors, expensive transition metal catalysts, and repeated purification steps. OECT microfabrication is mostly performed using cleanroom-based photolithography, hindering fast prototyping and widespread adoption of this technology for low-volume, low-cost applications.

To enable the transition from the laboratory to usable products, materials need to be cheap, scalable, and free from toxic precursors. Fabrication methods should enable high resolution while being affordable and allowing rapid prototyping. Here, I will discuss two of our recent works aimed at addressing these challenges.

From the materials perspective, I will show that blending a n-type conjugated polymer p(N-T) with large amounts of insulating commodity polymers (six times more) can improve OECT performance while drastically decreasing the amount of conjugated polymer used in the blend.^2,3 We found that the improvement in μC* is due to a dramatic increase in electronic mobility by two orders of magnitude, from 0.059 to 1.3 cm² V^-1 s^-1 for p(N-T):Polystyrene 10KDa 1:6. Moreover, devices made with this polymer blend show better stability, retaining 77% of the initial drain current after 60 minutes operation in contrast to 12% for pristine p(N-T). Moreover, I will present a scalable method based on cleanroom-free polymer patterning for OECT fabrication using ultrafast focused laser exposure.⁴ This approach enabled micrometer resolution in OECT fabrication while cutting down on the steps needed with conventional manufacturing using photolithography. The utility of this OECT manufacturing approach was demonstrated by fabricating complementary logic (inverters) and glucose biosensors, thereby showing its potential to accelerate OECT research.