Flexible electronics with highly thermal stability and mechanical strength are highly needed in advanced transportation systems. Semiconducting single-walled carbon nanotubes are one of the leading active materials for such thin film transistors because they are printable, flexible, thermally stable, and mechanically strong. Dielectrics with large capacitance are another major component, and polymer electrolytes are printed for flexible electronics, but they suffer from poor mechanical strength and low operating temperature. Here, a transparent, mechanically flexible, and thermally stable polyfluorinated electrolyte (PFE) is developed with high capacitance by curing printed polyfluorinated resin (PFR) and ionic liquid composite at high temperature. PFE inherits the mechanical flexibility and thermal stability from PFR. The immobilized ionic liquid inside the porous structures of PFE accounts for the high capacitance. With top-gated PFE, fully printed electronically pure single-chirality (6,5) single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) exhibit air stable, consistent, and reliable ambipolar characteristics with high transconductance (1 mS) and small subthreshold swing (<0.15 V dec(-1)) at low voltage in ambient air for p-type and n-type carriers, and >10(5) ON/OFF current ratio for both carriers under low operation voltage.