Ultraconformable Carbon Nanotube Thin-Film Transistors Fabricated on Sub-100-nm Substrate

Ultrathin flexible electronics are of great interest for next-generation wearable and biointegrated systems requiring high mechanical compliance and conformability. In this letter, carbon nanotube thin-film transistors (CNT TFTs) fabricated on an ultrathin polyimide (PI) substrate with a thickness of ~80 nm are demonstrated, resulting in a total device thickness of only$109.16~\pm ~3.33$nm. The ultrathin substrate is realized through an optimized solution-based process using diluted PI precursors and controlled thermal curing, yielding excellent uniformity with a root-mean-square surface roughness of 391.8 pm. The resulting CNT TFTs exhibit stable electrical characteristics, with a carrier mobility of$16.02~\pm ~1.30$cm2V${}^{-{1}}$s${}^{-{1}}$and anon/offratio of$\sim$$ 10^{{5}}$. Bending tests under different radii and cyclic deformation show that the devices maintain their electrical performance under mechanical stress. In addition, the ultrathin devices exhibit excellent conformability to curved and irregular surfaces, such as human fingertips. These results provide a feasible route toward ultraconformable flexible electronics for wearable and biointegrated applications.