Stable electrolyte dielectric engineered bottom-gate poly(3-hexylthiophene) transistors with enhanced mobility

In field-effect transistors (FETs), alternative device configurations present comprehensive testbeds for achieving optimum performance depending on the semiconductor families and gate dielectrics. However, these fabrication potentials are considerably limited in electrolyte-gated transistors, which traditionally use top-gated configurations. In this respect, bottom-gate transistors using electrolyte dielectric have been disregarded, and their device performance and operation mechanism have been unrevealed so far, despite the possibility to restrict the undesired motion of ions from the semiconducting channel. Here, bottom-gate solid-state electrolyte-gated organic transistor (EGOT) with remarkable field-effect mobility is reported. Fabricated bottom-gate/top-contact (BGTC) EGOTs using solid-state electrolyte gate insulator (SEGI) and benchmark poly(3-hexylthiophene) (P3HT) semiconductor, demonstrate the ability to achieve the stable device operation with remarkable hole mobility (μ) of 3.97 ± 0.48 cm2 V–1 s–1, surpassing the top-gate/bottom-contacts (TGBC) devices (μavg ≈ 3.56 ± 0.39 cm2 V–1 s–1). The high mobility in the BGTC EGOTs ensues from the interplay of the robust transition of the P3HT/SEGI interface, the absent ion penetration into the active permeable channel, the domination of electrostatic (field-effect) charging mechanism, and the orientations of P3HT crystallites. This new milestone provides an excellent framework for further improvements in the performance of EGOTs and related devices via electrostatic gating.