All‐Polymer Bulk‐Heterojunction Organic Electrochemical Transistors with Balanced Ionic and Electronic Transport

Abstract

The rapid development of organic electrochemical transistor (OECTs)‐based circuits brings new opportunities for next‐generation integrated bioelectronics. The all‐polymer bulk‐heterojunction (BHJ) offers an attractive, inexpensive alternative to achieve efficient ambipolar OECTs, and building blocks of logic circuits constructed from them, but have not been investigated to date. Here, the first all‐polymer BHJ‐based OECTs are reported, consisting of a blend of new p‐type ladder conjugated polymer and a state‐of‐the‐art n‐type ladder polymer. The whole ladder‐type polymer BHJ also proves that side chains are not necessary for good ion transport. Instead, the polymer nanostructures play a critical role in the ion penetration and transportation and thus in the device performance. It also provides a facile strategy and simplifies the fabrication process, forgoing the need to pattern multiple active layers. In addition, the development of complementary metal–oxide–semiconductor (CMOS)‐like OECTs allows the pursuit of advanced functional logic circuitry, including inverters and NAND gates, as well as for amplifying electrophysiology signals. This work opens a new approach to the design of new materials for OECTs and will contribute to the development of organic heterojunctions for ambipolar OECTs toward high‐performing logic circuits.

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

“…Recent work also showed the combination of p and n-type polymers in the form of a bulk heterojunction, where a p-type 6H-pyrrolo[3,2-b:4,5-b 0 ]bis [1,4]benzothiazine ladder (PBBTL) polymer was blended with BLL, producing an ambipolar OECT. 86 By optimizing the mass ratios of the individual polymers, the authors tuned the transport properties of each component of the bulk heterojunction, achieving a bicontinuous network of homogeneously distributed junctions between the PBBTL and BBL interfaces. Such combinations allow for extending the operation regime of OECTs.…”

n-Type semiconductors for organic electrochemical transistor applications

“…Another new design strategy was used to develop new channel materials for ambipolar OECTs, blending n-type and p-type materials together to form a bulkheterojunction (BHJ) structure, which is a very common structure in organic photovoltaics [74]. A n-type fullerene-based small molecule, PrC60MA, and a p-type polymer polythiophene, p(g2T-TT), were chosen to make the BHJ blend [105].…”

“…and the combination of n-and p-type blends in a bulk-heterojunction (BHJ) structure, such as the ladder polymers BBL and PBBTL [74] or the fullerene-based small molecule PrC60MA (Fig. 4) with p(g2T-TT) [105], which introduces a highly controllable, adaptable approach to OECT inverters.…”

“…4) with p(g2T-TT) [105], which introduces a highly controllable, adaptable approach to OECT inverters. enabling the device to track eye movement [74].…”

P- and N-dopable ambipolar bulk heterojunction thermoelectrics based on ladder-type conjugated polymers

“…Such a blend of p-and n-type conjugated polymers is analogous to the all-polymer bulk heterojunction (BHJ) OPVs that have shown a dramatic power efficiency improvement over the past decade, 21 and more recently in high-performance BHJ OECTs. 19 Interestingly, the use of p-and n-type conjugated polymer BHJ has not been demonstrated in OTEs, albeit the stimulating work on density of states engineering using pure p-or n-type blends reported by the groups of Katz, Campoy-Quiles and Kemerink. [22][23][24][25][26] Here, we describe for the first time the use of p-and n-type ladder conjugated polymer (PBBTL as p-type and BBL as n-type) blends that can be either p-or n-doped for OTEs (Fig.…”