Degassing and Doping Unlock the Longevity Code of OECTs
Organic electrochemical transistors (OECTs) are pivotal for bioelectronic interfaces, yet their operational stability is compromised by electrochemical cycling, environmental exposure, and parasitic reactions, leading to performance hysteresis. The prevailing reliance on mixed ionic-electronic conductors such as PEDOT:PSS exacerbates degradation through redox reactions, oxidative chain scission, dopant loss, and charge trapping, further aggravated by oxygen and water in the electrolyte. Conventional mitigation strategies—redox-stable polymer synthesis, hydrophobic side chains, and physical encapsulation—offer only modest stability improvements while impeding ion transport, increasing response time, or reducing sensitivity, and often require complex fabrication incompatible with scalable manufacturing. Le et al. (Nat. Electron. 2025, 8, 116–126) introduce a synergistic approach combining solvent degassing and chemical doping. Systematic degassing of processing solvents via freeze-evacuation-thawing cycles or inert gas injection yields films with higher crystallinity and fewer carbonyl defects. Ultraviolet photoelectron spectroscopy reveals a work function shift from 4.0 eV in degassed chloroform to 4.3 eV in ambient chloroform for p(g3T2), underscoring oxygen's role as an uncontrolled p-dopant. The introduction of fluorinated fullerene (C60F48) as a stable p-dopant further mitigates degradation. This dual strategy preserves ionic-electronic coupling and manufacturability, providing a blueprint for robust organic bioelectronic devices with enhanced longevity.