Inkjet Printed Circuits on Flexible and Rigid Substrates Based on Ambipolar Carbon Nanotubes with High Operational Stability

Inkjet printed ambipolar transistors and circuits with high operational stability are demonstrated on flexible and rigid substrates employing semiconducting single-walled carbon nanotubes (SWCNTs). All patterns, which include electrodes, semiconductors, and vias, are realized by inkjet printing without the use of rigid physical masks and photolithography. An Al₂O₃ layer deposited on devices by atomic layer deposition (ALD) transforms p-type SWCNT thin-film transistors (TFTs) into ambipolar SWCNT TFTs and encapsulates them effectively. The ambipolar SWCNT TFTs have balanced electron and hole mobilities, which facilitates their use in multicomponent circuits. For example, a variety of logic gates and ring oscillators are demonstrated based on the ambipolar TFTs. The three-stage ring oscillator operates continuously for longer than 80 h under ambient conditions with only slight deviations in oscillation frequency. The successful demonstration of ambipolar devices by inkjet printing will enable a new class of circuits that utilize n-channel, p-channel, and ambipolar circuit components.