Synergistic Effect of Multi‐Walled Carbon Nanotubes and Ladder‐Type Conjugated Polymers on the Performance of N‐Type Organic Electrochemical Transistors

Abstract

Organic electrochemical transistors (OECTs) have the potential to revolutionize the field of organic bioelectronics. To date, most of the reported OECTs include p-type (semi-)conducting polymers as the channel material, while n-type OECTs are yet at an early stage of development, with the best performing electron-transporting materials still suffering from low transconductance, low electron mobility, and slow response time. Here, the high electrical conductivity of multi-walled carbon nanotubes (MWCNTs) and the large volumetric capacitance of the ladder-type π-conjugated redox polymer poly(be nzimidazobenzophenanthroline) (BBL) are leveraged to develop n-type OECTs with record-high performance. It is demonstrated that the use of MWCNTs enhances the electron mobility by more than one order of magnitude, yielding fast transistor transient response (down to 15 ms) and high μC* (electron mobility × volumetric capacitance) of about 1 F cm −1 V −1 s −1 . This enables the development of complementary inverters with a voltage gain of >16 and a large worst-case noise margin at a supply voltage of <0.6 V, while consuming less than 1 µW of power.

Stable organic electrochemical neurons based on p-type and n-type ladder polymers

“…Considered altogether, these inverter characteristics are among the best reported for sub-1 V complementary inverters. 46,49,52,63,65–69…”

A guide for the characterization of organic electrochemical transistors and channel materials

“…The planarity and rigidity of the BBL backbone promote electron delocalization and facilitate intramolecular charge transfer. The high performance of enhancement mode BBL OECTs have been leveraged to build complementary circuits [81][82][83] and an ion sensor, 84 as well as neuromorphic devices. 85 Furthermore, BBL represents the first demonstration of an n-type depletion mode OECT, where BBL was chemically reduced with PEI in printable ethanol-based ink.…”

Salts as Additives: A Route to Improve Performance and Stability of n-Type Organic Electrochemical Transistors

“…For example, including a “bad” solvent in the n-type polymer-casting solution induced chain aggregation, which led to a morphology enabling better charge transport . Combining n-type polymers with multiwalled carbon nanotubes (CNTs) facilitated charge transport and improved device speed due to a conductive percolative network provided by CNTs . An approach rarely explored for OECTs but is very effective for OFETs is using molecular dopants to control materials’ charge carrier density and conductivity .…”