Performance enhancement of aluminium-gated poly(3-hexylthiophene) transistors with polymer electrolyte/PMMA bilayer gate dielectrics

Tremendous progress in device performance has been realized in electrolyte-gated field-effect transistors (FETs). However, due to the formation of oxides at the metal/electrolyte interface, electrochemically stable and corrosion-resistant noble metals (e.g., gold, platinum, or palladium) have been utilized, which makes device fabrication expensive. In this study, we report an enhanced performance in aluminium (Al)-gated poly(3-hexylthiophene) (P3HT) transistors with polymer electrolyte/poly(methyl methacrylate) (PMMA) bilayer gate dielectrics. This cost-effective Al-gated transistor devices with polymer electrolyte/PMMA bilayer dielectrics measured improved operational stability and hole mobility of ∼0.06 cm² V⁻¹ s⁻¹ at low operating voltage of −15 V compared to the control Al-gated FETs with PMMA dielectric (∼0.03 cm² V⁻¹ s⁻¹) and Al-gated devices with electrolyte dielectric (∼10⁻⁴ cm² V⁻¹ s⁻¹). The exceptional performance in the FETs with bilayer gate dielectric would be attributed to an improved charge transport and a robust vacuum metalized Al/PMMA interface in contrast to the electrolyte-gated FETs, which was severely influenced by the formation of aluminium oxide layer (Al₂O₃) at the Al/dielectric interface. This study provides a practical approach for fabricating low-cost, low-voltage, and high-performance FET devices with hybrid polymer electrolyte/PMMA bilayer dielectrics.