Bistable Organic Electrochemical Transistors: Enthalpy vs. Entropy

TL;DR

This paper introduces a thermodynamic model explaining bistability in organic electrochemical transistors, validated through experiments, revealing deviations from classical statistics, and demonstrating a novel single-device Schmitt trigger for advanced computing applications.

Contribution

The study provides a new thermodynamic framework for understanding bistability in OECTs, validated by experiments, and demonstrates a compact single-device Schmitt trigger, advancing non-conventional computing.

Findings

Validated thermodynamic model explains bistability.

Revealed deviations from Boltzmann statistics.

Demonstrated a single-OECT Schmitt trigger.

Abstract

Organic electrochemical transistors (OECTs) underpin a range of emerging technologies, from bioelectronics to neuromorphic computing, owing to their unique coupling of electronic and ionic charge carriers. In this context, various OECT systems exhibit significant hysteresis in their transfer curve, which is frequently leveraged to achieve non-volatility. Meanwhile, a general understanding of its physical origin is missing. Here, we introduce a thermodynamic framework that readily explains the emergence of bistable OECT operation via the interplay of enthalpy and entropy. We validate this model through temperature-resolved characterizations, material manipulation, and thermal imaging. Further, we reveal deviations from Boltzmann statistics for the subthreshold swing and reinterpret existing literature. Capitalizing on these findings, we finally demonstrate a single-OECT Schmitt trigger, thus compacting a multi-component circuit into a single device. These insights provide a fundamental advance for OECT physics and its application in non-conventional computing, where symmetry-breaking phenomena are pivotal to unlock new paradigms of information processing.