Printed electronics offer a breakthrough in the penetration of information technology into everyday life. The possibility of printing electronic circuits will further promote the spread of the Internet of Things applications. Inks based on graphene have a chance to dominate this technology, as they potentially can be low cost and applied directly on materials like textile and paper. Here we report the environmentally sustainable route of production of graphene ink suitable for screen-printing technology. The use of non-toxic solvent Dihydrolevoglucosenone (Cyrene) significantly speeds up and reduces the cost of the liquid phase exfoliation of graphite. Printing with our ink results in very high conductivity (7.13 × 10⁴ S m⁻¹) devices, which allows us to produce wireless connectivity antenna operational from MHz to tens of GHz, which can be used for wireless data communication and energy harvesting, which brings us very close to the ubiquitous use of printed graphene technology for such applications.

Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium–gallium–zinc–oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning.

A graphene ballistic rectifier is used in conjunction with an antenna to demonstrate a rectenna as a terahertz (THz) detector. A small-area (<1 μm²) local gate is used to adjust the Fermi level in the device to optimize the output while minimizing the impact on the cutoff frequency. The device operates in both n- and p-type transport regimes and shows a peak extrinsic responsivity of 764 V/W and a corresponding noise equivalent power of 34 pW Hz^–1/2 at room temperature with no indications of a cutoff frequency up to 0.45 THz. The device also demonstrates a linear response for more than 3 orders of magnitude of input power due to its zero threshold voltage, quadratic current–voltage characteristics and high saturation current. Finally, the device is used to take an image of an optically opaque object at 0.685 THz, demonstrating potential in both medical and security imaging applications.

Although graphene has the longest mean free path of carriers of any known electronic material, very few novel devices have been reported to harness this extraordinary property. Here we demonstrate a ballistic nano-rectifier fabricated by creating an asymmetric cross-junction in single-layer graphene sandwiched between boron nitride flakes. A mobility ∼200,000 cm² V⁻¹ s⁻¹is achieved at room temperature, well beyond that required for ballistic transport. This enables a voltage responsivity as high as 23,000 mV mW⁻¹with a low-frequency input signal. Taking advantage of the output channels being orthogonal to the input terminals, the noise is found to be not strongly influenced by the input. Hence, the corresponding noise-equivalent power is as low as 0.64 pW Hz^−1/2. Such performance is even comparable to superconducting bolometers, which however need to operate at cryogenic temperatures. Furthermore, output oscillations are observed at low temperatures, the period of which agrees with the lateral size quantization.

Significance: The advent of thin-film electronics and the development of new materials, such as oxide semiconductors, bring great opportunities for new device designs and applications. A source-gated transistor (SGT) is created by combining two fundamental building blocks of electronics: a thin-film transistor and a Schottky diode. By developing a methodology to manipulate the source barrier profile, an extremely high gain of 29,000 is achieved, previously unthinkable with a single component. The SGT design overcomes several major bottlenecks to using oxide semiconductors in large-scale applications and broadens the range of channel materials beyond standard semiconductors. These advantages combined with an analytical theory confirmed by simulations and experiments demonstrate the potential of SGTs to be a fundamental component for thin-film electronics.

Indium-gallium-zinc-oxide thin-film transistors (TFTs) with solution-processed, high-capacitance Al _x O _y gate dielectrics have been fabricated at room temperature. The morphology and electrical properties of the anodized, ultra-thin AlxOy film have been studied. Several anodization voltages were used to create the gate dielectrics and the results showed that the TFTs gated with aluminum oxide anodized at 2.3 V (~3 nm) exhibited the best performance. The TFTs operate at an ultra-low voltage of 1 V with a high current on/off ratio >10 ⁵ and a subthreshold swing (SS) as low as 68 mV/dec, which is very close to the theoretical limit of SS at 300 K. As a result, the presented devices possess a great potential for low-power electronics.