The advantages of printed electronics and semiconducting single-walled carbon nanotubes (SWCNTs) are combined for the first time for display electronics. Conductive silver ink and 98% semiconductive SWCNT solutions are used to print back-gated thin film transistors with high mobility, high on/off ratio, and high current carrying capacity. In addition, with printed polyethylenimine with LiClO4 as the gating material, fully printed top-gated devices have been made to work as excellent current switches for organic light emitting diodes (OLEDs). An OLED driving circuit composed of two top-gated fully printed transistors has been fabricated, and the successful control over external OLED is demonstrated. Our work demonstrates the significant potential of using printed carbon nanotube electronics for display backplane applications.

Due to extraordinary electrical properties, preseparated, high purity semiconducting carbon nanotubes hold great potential for thin-film transistors (TFTs) and integrated circuit applications. One of the main challenges it still faces is the fabrication of air-stable n-type nanotube TFTs with industry-compatible techniques. Here in this paper, we report a novel and highly reliable method of converting the as-made p-type TFTs using preseparated semiconducting nanotubes into air-stable n-type transistors by adding a high-κ oxide passivation layer using atomic layer deposition (ALD). The n-type devices exhibit symmetric electrical performance compared with the p-type devices in terms of on-current, on/off ratio, and device mobility. Various factors affecting the conversion process, including ALD temperature, metal contact material, and channel length, have also been systematically studied by a series of designed experiments. A complementary metal-oxide-semiconductor (CMOS) inverter with rail-to-rail output, symmetric input/output behavior, and large noise margin has been further demonstrated. The excellent performance gives us the feasibility of cascading multiple stages of logic blocks and larger scale integration. Our approach can serve as the critical foundation for future nanotube-based thin-film macroelectronics.

Active matrix organic light-emitting diode (AMOLED) display holds great potential for the next generation visual technologies due to its high light efficiency, flexibility, lightweight, and low-temperature processing. However, suitable thin-film transistors (TFTs) are required to realize the advantages of AMOLED. Preseparated, semiconducting enriched carbon nanotubes are excellent candidates for this purpose because of their excellent mobility, high percentage of semiconducting nanotubes, and room-temperature processing compatibility. Here we report, for the first time, the demonstration of AMOLED displays driven by separated nanotube thin-film transistors (SN-TFTs) including key technology components, such as large-scale high-yield fabrication of devices with superior performance, carbon nanotube film density optimization, bilayer gate dielectric for improved substrate adhesion to the deposited nanotube film, and the demonstration of monolithically integrated AMOLED display elements with 500 pixels driven by 1000 SN-TFTs. Our approach can serve as the critical foundation for future nanotube-based thin-film display electronics.

We report high-performance arsenic (As)-doped indium oxide (In(2)O(3)) nanowires for transparent electronics, including their implementation in transparent thin-film transistors (TTFTs) and transparent active-matrix organic light-emitting diode (AMOLED) displays. The As-doped In(2)O(3) nanowires were synthesized using a laser ablation process and then fabricated into TTFTs with indium-tin oxide (ITO) as the source, drain, and gate electrodes. The nanowire TTFTs on glass substrates exhibit very high device mobilities (approximately 1490 cm(2) V(-1) s(-1)), current on/off ratios (5.7 x 10(6)), steep subthreshold slopes (88 mV/dec), and a saturation current of 60 microA for a single nanowire. By using a self-assembled nanodielectric (SAND) as the gate dielectric, the device mobilities and saturation current can be further improved up to 2560 cm(2) V(-1) s(-1) and 160 microA, respectively. All devices exhibit good optical transparency (approximately 81% on average) in the visible spectral range. In addition, the nanowire TTFTs were utilized to control green OLEDs with varied intensities. Furthermore, a fully integrated seven-segment AMOLED display was fabricated with a good transparency of 40% and with each pixel controlled by two nanowire transistors. This work demonstrates that the performance enhancement possible by combining nanowire doping and self-assembled nanodielectrics enables silicon-free electronic circuitry for low power consumption, optically transparent, high-frequency devices assembled near room temperature.

We describe growth and characterization of N-face GaN-based high electron mobility structures using plasma-assisted molecular beam epitaxy (MBE) on C-face SiC substrates. A two-step buffer approach consisting of a low Ga-flux followed by high Ga-flux was used to achieve smooth morphologies and threading dislocation (TD) densities as low as 1.5×1010 cm-2. These TD densities are comparable to the lowest achieved on Ga-face GaN grown by MBE on Si-face SiC. Secondary ion mass spectrometry measurements were carried out to study O, C, and Si incorporation. Hall, capacitance–voltage and transfer length method measurements on GaN/AlGaN/GaN modulation-doped heterostructures were found to match simulations, and a charge of 1×1013 cm-2 with electron mobility above 1000 cm2 V-1 s-1 was measured.