Low-voltage high-performance flexible digital and analog circuits based on ultrahigh-purity semiconducting carbon nanotubes.

Carbon nanotube (CNT) thin-film transistor (TFT) is a promising candidate for flexible and wearable electronics. However, it usually suffers from low semiconducting tube purity, low device yield, and the mismatch between p- and n-type TFTs. Here, we report low-voltage and high-performance digital and analog CNT TFT circuits based on high-yield (19.9%) and ultrahigh purity (99.997%) polymer-sorted semiconducting CNTs. Using high-uniformity deposition and pseudo-CMOS design, we demonstrated CNT TFTs with good uniformity and high performance at low operation voltage of 3 V. We tested forty-four 2-µm channel 5-stage ring oscillators on the same flexible substrate (1,056 TFTs). All worked as expected with gate delays of 42.7 ± 13.1 ns. With these high-performance TFTs, we demonstrated 8-stage shift registers running at 50 kHz and the first tunable-gain amplifier with 1,000 gain at 20 kHz. These results show great potentials of using solution-processed CNT TFTs for large-scale flexible electronics.

Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics.

Increasing performance demands and shorter use lifetimes of consumer electronics have resulted in the rapid growth of electronic waste. Currently, consumer electronics are typically made with nondecomposable, nonbiocompatible, and sometimes even toxic materials, leading to serious ecological challenges worldwide. Here, we report an example of totally disintegrable and biocompatible semiconducting polymers for thin-film transistors. The polymer consists of reversible imine bonds and building blocks that can be easily decomposed under mild acidic conditions. In addition, an ultrathin (800-nm) biodegradable cellulose substrate with high chemical and thermal stability is developed. Coupled with iron electrodes, we have successfully fabricated fully disintegrable and biocompatible polymer transistors. Furthermore, disintegrable and biocompatible pseudo-complementary metal-oxide-semiconductor (CMOS) flexible circuits are demonstrated. These flexible circuits are ultrathin (<1 µm) and ultralightweight (∼2 g/m2) with low operating voltage (4 V), yielding potential applications of these disintegrable semiconducting polymers in low-cost, biocompatible, and ultralightweight transient electronics.