Bridging Mode-Specific Performance Gaps in Organic Charge-Modulated Transistor Platforms via Coupled Interfacial Boundary Engineering

Abstract

Organic charge-modulated field-effect transistors (OCMFETs) offer a powerful route to charge/potential-amplified sensing, yet their induced-gating operation readily magnifies dielectric/interfacial nonidealities, causing key metrics—field-effect mobility (μFET), threshold voltage (Vth), and subthreshold swing (SS)—to decouple from those obtained in organic field-effect transistor (OFET) mode on the same platform. Here, we establish a design framework that co-regulates dielectric bulk properties and the electrical boundary conditions at the dielectric/organic semiconductor interface to align effective gating across operational modes. By tuning the anodizing voltage, the thickness, surface state, and dielectric/insulating characteristics of anodized aluminum oxide (AlOx) are systematically controlled, while a tetradecylphosphonic acid (TDPA) self-assembled monolayer (SAM) suppresses surface polarity and trap-associated charge instability. Quantifying the mismatch as ΔμFET, ΔVth, and ΔSS (= OCMFET−OFET), we find that TDPA-SAM reduces both the magnitude and dispersion of Δ(parameters), indicating convergence of effective gating between induced and direct gating. Transfer hysteresis and bias-stress-induced drain current decay and threshold-voltage drift are concurrently alleviated. These results show that combining bulk dielectric control (thickness) with interfacial boundary-condition engineering converts the structural sensitivity of OCMFETs into a manageable design variable, thereby minimizing OFET−OCMFET performance mismatch and improving the reproducibility and interpretability of multimode transistor-based sensor platforms.