Molecular Design Strategies toward Improvement of Charge Injection and Ionic Conduction in Organic Mixed Ionic–Electronic Conductors for Organic Electrochemical Transistors

Abstract

Expanding the toolbox of the biology and electronics mutual conjunction is a primary aim of bioelectronics. The organic electrochemical transistor (OECT) has undeniably become a predominant device for mixed conduction materials, offering impressive transconduction properties alongside a relatively simple device architecture. In this review, we focus on the discussion of recent material developments in the area of mixed conductors for bioelectronic applications by means of thorough structure–property investigation and analysis of current challenges. Fundamental operation principles of the OECT are revisited, and characterization methods are highlighted. Current bioelectronic applications of organic mixed ionic–electronic conductors (OMIECs) are underlined. Challenges in the performance and operational stability of OECT channel materials as well as potential strategies for mitigating them, are discussed. This is further expanded to sketch a synopsis of the history of mixed conduction materials for both p- and n-type channel operation, detailing the synthetic challenges and milestones which have been overcome to frequently produce higher performing OECT devices. The cumulative work of multiple research groups is summarized, and synthetic design strategies are extracted to present a series of design principles that can be utilized to drive figure-of-merit performance values even further for future OMIEC materials.

Synthetic Nuances to Maximize n-Type Organic Electrochemical Transistor and Thermoelectric Performance in Fused Lactam Polymers

“… 10 Hence, to improve OECT device performance, an in-depth understanding of the structure–property relationships governing OMIEC performance is crucial for both the mobility and volumetric capacitance of the OMIEC to be optimized. 11 …”

Hybrid Organic-Inorganic Materials and Interfaces With Mixed Ionic-Electronic Transport Properties: Advances in Experimental and Theoretical Approaches

“…There are a lot of recent examples of h OI materials with promising mixed ionic-electronic transport properties in different applications such as lithium and sodium-ion battery electrode ( Sengodu and Deshmukh, 2015 ) and bio-electronic materials ( Kousseff et al, 2022 ; Kukhta et al, 2022 ). There are also recent reviews on the most relevant and popular techniques that can be useful to characterize experimentally the mixed ionic-electronic transport in h OI materials ( Romero et al, 2020 ; Wu et al, 2022 ).…”

The effect of side chain engineering on conjugated polymers in organic electrochemical transistors for bioelectronic applications

“…High selectivity and sensitivity, signal transduction and amplification, permeability, and operational stability in plentiful biologically important electrolytes bring OECTs to the forefront of bioelectronic research. [24][25][26] It is the ability of the polymer channel material to uptake ions and other metabolites from the interfacing electrolyte and transport electronic charge carriers (holes and/or electrons), resulting in mixed ionic and electronic conductance, that underpins the superior performance of OECTs in bioelectronic applications. 27 Mixed conductance, permeability, and conformability, essential for the OECT operation, can be achieved via the utilisation of organic mixed ionic-electronic conductors (OMIECs).…”