Empowering Bioelectronics with Supramolecular Nanoarchitectonics: PEDOT-Based Organic Electrochemical Transistors with Tunable Electronic Properties

Abstract

Organic bioelectronics has the potential to unlock the utmost innovation in medicine and healthcare through the combination of biological and digital realms. Particularly, organic electrochemical transistors (OECTs) are a promising class of bioelectronics transducer. Nevertheless, a fabrication strategy is needed to lower the access barrier to the OECTs, thereby expediting product development and innovation. In this work, we present a supramolecular approach with simple equipment to prepare conductive films based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, integrated with cationic molecular blocks for OECTs manufacturing. By employing the layer-by-layer (LbL) self-assembly technique, we facilely prepared transistor channels of PEDOT:PSS integrated with either the surfactant cetyltrimethylammonium bromide, CTAB, or the polyelectrolyte poly(diallyldimethylammonium chloride), PDADMAC, with nanometric precision. Both cationic blocks feature positively charged quaternary amines but possess different mesogenic and surfactant features. The PEDOT:PSS/CTAB system yields an electrical conductivity of 275 S m–1, which is 4 orders of magnitude higher than those integrated with PDADMAC (0.0531 S m–1). This enhancement is attributed to CTAB integration, which boosts the PEDOT:PSS charge transport, while PDADMAC diminishes it. The electronic performance indicators of OECTs (current at the on-state, Imax, threshold potential, VTH, transconductance, gm) are easily tuned by adjusting the thickness of the transistor channel film. The cycling stability of the transistor channel is 8-fold enhanced by coating it with a protective layer using nonelectroactive polymers. These OECTs exhibit a gm of 2.21 mS, a μC* product (μ is the hole mobility, and C* is the capacitance per unit of volume) of 0.23 F cm–1 V–1 s–1, and on- and off-switching times, τ, of 24.2 and 12.3 ms, respectively. Their performance was comparable to or better than OECTs with channels prepared using techniques based on equipment of higher complexity and cost. Finally, we demonstrate the utility of these facilely prepared OECTs in biosensing the neurotransmitter dopamine with an exceptional sensitivity of 279 mV/decade and good operation range (1–300 μM) and reversibility.