Organic electrochemical transistors (OECTs) hold promise for developing a variety of high‐performance (bio‐)electronic devices/circuits. While OECTs based on p‐type semiconductors have achieved tremendous progress in recent years, n‐type OECTs still suffer from low performance, hampering the development of power‐efficient electronics. Here, it is demonstrated that fine‐tuning the molecular weight of the rigid, ladder‐type n‐type polymer poly(benzimidazobenzophenanthroline) (BBL) by only one order of magnitude (from 4.9 to 51 kDa) enables the development of n‐type OECTs with record‐high geometry‐normalized transconductance (
- Award ID(s):
- 1751308
- NSF-PAR ID:
- 10329071
- Date Published:
- Journal Name:
- Polymer Chemistry
- Volume:
- 13
- Issue:
- 19
- ISSN:
- 1759-9954
- Page Range / eLocation ID:
- 2764 to 2775
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract g m,norm ≈ 11 S cm−1) and electron mobility × volumetric capacitance (µC * ≈ 26 F cm−1 V−1s−1), fast temporal response (0.38 ms), and low threshold voltage (0.15 V). This enhancement in OECT performance is ascribed to a more efficient intermolecular charge transport in high‐molecular‐weight BBL than in the low‐molecular‐weight counterpart. OECT‐based complementary inverters are also demonstrated with record‐high voltage gains of up to 100 V V−1and ultralow power consumption down to 0.32 nW, depending on the supply voltage. These devices are among the best sub‐1 V complementary inverters reported to date. These findings demonstrate the importance of molecular weight in optimizing the OECT performance of rigid organic mixed ionic–electronic conductors and open for a new generation of power‐efficient organic (bio‐)electronic devices. -
Abstract Organic electrochemical transistors (OECTs) have gained considerable attention due to their potential applications in emerging biosensor platforms. The use of conjugated polyelectrolytes (CPEs) as active materials in OECTs is particularly advantageous owing to their functional, water‐processable, and biocompatible nature, as well as their tunable electronic and ionic transport properties. However, there exists a lack of systematic studies of the structure‐property relationships of these materials with respect to OECT performance. This study shows how by tuning the molecular weight of self‐doped CPE (CPE‐K) it is possible to fabricate OECTs with a
µC *value of 14.7 F cm−1V−1s−1, one order of magnitude higher than previously reported CPE‐based devices. Furthermore, OECTs with a transconductance of 120 mS are demonstrated via device engineering. While CPE‐K batches with different molecular weights show good doping behavior and high volumetric capacitance, as confirmed by spectroelectrochemistry and electrochemical impedance spectroscopy, the medium molecular weight possesses the highest carrier mobility of ≈0.1 cm2V−1s−1leading to the highest transconductance. The enhanced charge transport is due to a favorable charge percolation pathway, as revealed by the combination of X‐ray analysis and conductive atomic force microscope. These insights provide guidelines for further improving the performance of CPE‐based OECTs. -
Abstract Organic electrochemical transistors (OECTs) have exhibited promising performance as transducers and amplifiers of low potentials due to their exceptional transconductance, enabled by the volumetric charging of organic mixed ionic/electronic conductors (OMIECs) employed as the channel material. OECT performance in aqueous electrolytes as well as the OMIECs’ redox activity has spurred a myriad of studies employing OECTs as chemical transducers. However, the OECT's large (potentiometrically derived) transconductance is not fully leveraged in common approaches that directly conduct chemical reactions amperometrically within the OECT electrolyte with direct charge transfer between the analyte and the OMIEC, which results in sub‐unity transduction of gate to drain current. Hence, amperometric OECTs do not truly display current gains in the traditional sense, falling short of the expected transistor performance. This study demonstrates an alternative device architecture that separates chemical transduction and amplification processes on two different electrochemical cells. This approach fully utilizes the OECT's large transconductance to achieve current gains of 103and current modulations of four orders of magnitude. This transduction mechanism represents a general approach enabling high‐gain chemical OECT transducers.
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Abstract Conjugated‐polymer‐based organic electrochemical transistors (OECTs) are being studied for applications ranging from biochemical sensing to neural interfaces. While new polymers that interface digital electronics with the aqueous chemistry of life are being developed, the majority of high‐performance organic transistor materials are poor at transporting biologically relevant ions. Here, the operating mode of an organic transistor is changed from that of an electrolyte‐gated organic field‐effect transistor (EGOFET) to that of an OECT by incorporating an ion exchange gel between the active layer and the aqueous electrolyte. This device works by taking up biologically relevant ions from solution and injecting more hydrophobic ions into the active layer. Using poly[2,5‐bis(3‐tetradecylthiophen‐2‐yl) thieno[3,2‐b]thiophene] as the active layer and a blend of an ionic liquid, 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide, and poly(vinylidene fluoride‐
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null (Ed.)Organic electrochemical transistors (OECTs) have been revived as potentially versatile platforms for bioelectronic applications due to their high transconductance, direct ionic-electronic coupling, and unique form factors. This perceived applicability to bioelectronics can be attributed to the incorporation of organic mixed conductors that facilitate both ionic and electronic transport, enabling material-inherent translation from biological signals to abiotic readouts. In the past decade, multiple synthetic breakthroughs have yielded channel materials that exhibit significant hole/electron transport while displaying electroactivity in aqueous media. Yet, implicit in the rationale of OECTs as bioelectronic devices is they can be fabricated to be mechanically compatible with biological systems, even though unified guidelines for deformable OECTs remain unclear. In this Perspective, we highlight recent advances for imparting deformability. Specifically, materials selection, design, and chemistry for integral parts of the transistor – substrate, electrolyte, interconnects, and (polymeric) channel materials—will be discussed in the context of benchmarks set by select bioelectronics applications. We conclude by identifying key areas for future research towards mechanically compliant OECTs.more » « less