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Semiconducting single-wall carbon nanotubes are very promising materials in printed electronics due to their excellent mechanical and electrical property, outstanding printability, and great potential for flexible electronics. Nonetheless, developing scalable and low-cost approaches for manufacturing fully printed high-performance single-wall carbon nanotube thin-film transistors remains a major challenge. Here we report that screen printing, which is a simple, scalable, and cost-effective technique, can be used to produce both rigid and flexible thin-film transistors using separated single-wall carbon nanotubes.
The USC Nanolab developed fully printed top-gated nanotube thin-film transistors on rigid and flexible substrates exhibit decent performance, with mobility up to 7.67, on/off ratio of 10E4 to 10E5, minimal hysteresis, and low operation voltage (<10 V). In addition, outstanding mechanical flexibility of printed nanotubethin-film transistors (bent with radius of curvature down to 3 mm) and driving capability for organic light-emitting diode have been demonstrated. Given the high performance of the fully screen-printed single-wall carbon nanotube thin-film transistors, we believe screen printing stands as a low-cost, scalable, and reliable approach to manufacture high-performance nanotube thin-film transistors for application in display electronics. Moreover, this technique may be used to fabricate thin-film transistors based on other materials for large-area flexible macroelectronics, and low-cost display electronics. Paper Click Here
Achieving printed complementary macro electronics solely based on CNTs is difficult because it is still challenging to make reliable n-type CNT transistors. In this paper, we report threshold voltage (Vth) tuning and printing of complementary transistors and inverters composed of thin films of CNTs and indium zinc oxide (IZO) as p-type and n-type transistors, respectively. We have optimized the Vth of p-type transistors by comparing Ti/Au and Ti/Pd as source/drain electrodes, and observed that CNT transistors with Ti/Au electrodes exhibited enhancement mode operation. In addition, the optimized In:Zn ratio offers good n-type transistors with high on-state current (Ion) and enhancement mode operation.Furthermore, by printing a CNT thin film and an IZO thin film on the same substrate, we have fabricated a complementary inverter with an output swing of 99.6% of the supply voltage and a voltage gain of 16.9. This work shows the promise of the hybrid integration of p-type CNT and n-type IZO for complementary transistors and circuits.
“Threshold voltage tuning and printed complementary transistors and inverters based on thin films of carbon nanotubes and indium zinc oxide” P. Vuttipittayamongkol, F. Wu, H. Chen, X. Cao, B. Liu and C. Zhou Nano Research (2014) DOI 10.1007/s12274-014-0596-7 (PDF) (Suppl. Info.)
Aneeve is developing wide bandgap channel materials such as ZnO and IGZO that are able to be printed and microelectronic fabricated into devices for high speed circuits, microwave amplifiers, ultra-low power circuits, sensors, and thin film circuits. Wide bandgap materials have several characteristics that make them useful compared to lower bandgap materials. The higher energy gap gives devices the ability to operate at higher temperatures,and for some applications, allows devices to switch larger voltages. The wide bandgap also brings the electronic transition energy into the range of the energy of visible light, and hence light-emitting devices such as light-emitting diodes (LEDs). Wide bandgap semiconductors can also be used in RF signal processing. Silicon-based power transistors are reaching limits of operating frequency, breakdown voltage, and power density. Wide bandgap materials can be used in high-temperature and power switching applications.
IGZO is a revolutionary, transparent compound semiconductor that Sharp is the first to successfully mass-produce and bring to market. IGZO opens the door to countless breakthroughs, from crystal clear displays to lower energy and even life-changing technology of the future.
In a paper recently published in Nature Communications, we have overcome a major issue in carbon nanotube technology by developing a flexible, energy-efficient hybrid circuit combining carbon nanotube thin film transistors with other thin film transistors. This hybrid could take the place of silicon as the traditional transistor material used in electronic chips, since carbon nanotubes are more transparent, flexible, and can be processed at a lower cost.