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  • Working paper
    Carey T, Arbab A, Anzi L, Bristow H, Hui F, Bohm S, Wyatt-Moon G, Flewitt A, Wadsworth A, Gasparini N, Kim JM, Lanza M, McCulloch I, Sordan R, Torrisi Fet al., 2020,

    Inkjet printed circuits with two-dimensional semiconductor inks for high-performance electronics

    , Publisher: arXiv

    Air-stable semiconducting inks suitable for complementary logic are key tocreate low-power printed integrated circuits (ICs). High-performance printableelectronic inks with two-dimensional materials have the potential to enable thenext generation of high performance, low-cost printed digital electronics. Herewe demonstrate air-stable, low voltage (< 5 V) operation of inkjet-printedn-type molybdenum disulfide (MoS2) and p-typeindacenodithiophene-co-benzothiadiazole (IDT-BT) field-effect transistors(FETs), estimating a switching time of {\tau} ~ 3.3 {\mu}s for the MoS2 FETs.We achieve this by engineering high-quality MoS2 and air-stable IDT-BT inkssuitable for inkjet-printing complementary pairs of n-type MoS2 and p-typeIDT-BT FETs. We then integrate MoS2 and IDT-BT FETs to realise inkjet-printedcomplementary logic inverters with a voltage gain |Av| ~ 4 when in resistiveload configuration and |Av| ~ 1.36 in complementary configuration. Theseresults represent a key enabling step towards ubiquitous long-term stable,low-cost printed digital ICs.

  • Journal article
    Schütt F, Zapf M, Signetti S, Strobel J, Krüger H, Röder R, Carstensen J, Wolff N, Marx J, Carey T, Schweichelt M, Ivo Terasa M, Siebert L, Hong H-K, Kaps S, Fiedler B, Kumar Mishra Y, Lee Z, Pugno N, Kienle L, Ferrari AC, Torrisi F, Ronning C, Adelung Ret al., 2020,

    Conversionless efficient and broadband laser light diffusers for high brightness illumination applications

    , Nature Communications, Vol: 11, Pages: 1-10, ISSN: 2041-1723

    Laser diodes (LDs) are considered the next generation of ultra-efficient light sources. However, state-of-the-art LD-based lighting systems rely on light-converting phosphorous materials, which strongly limit the efficiency, lifetime as well as the achievable light output due to energy losses, saturation, thermal degradation and low irradiance levels. Here, we demonstrate a macroscopically expanded, three-dimensional diffuser composed of interconnected hollow hexagonal boron nitride microtubes with nanoscopic wall-thickness, acting as an artificial solid fog, capable of withstanding ~10 times the irradiance level of remote phosphors. Indeed, in contrast to phosphors, no light conversion is required as the diffuser relies solely on strong broadband (full visible range) lossless multiple light scattering events, enabled by a highly porous (> 99.99%) non-absorbing nanoarchitecture, resulting in efficiencies of up to 98 %. This can unleash the potential of lasers for high-brightness lighting applications, such as automotive headlights, projection technology or lighting for large spaces.

  • Conference paper
    Mezzapesa FP, Garrasi K, Schmidt J, Salemi L, Li L, Davies AG, Linfield EH, Carey T, Torrisi F, Ferrari AC, Vitiello MSet al., 2020,

    Semiconductor THz frequency combs exploiting solution processed graphene

    , 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), Publisher: IEEE, ISSN: 2162-2027
  • Journal article
    Qiang S, Carey T, Arbab A, Song W, Wang C, Torrisi Fet al., 2019,

    Wearable solid-state capacitors based on two-dimensional material all-textile heterostructures

    , Nanoscale, Vol: 11, Pages: 9912-9919, ISSN: 2040-3364

    Two dimensional (2D) materials are a rapidly growing area of interest for wearable electronics, due to their flexible and unique electrical properties. All-textile based wearable electronic components are key to enable future wearable electronics. Single component electrical elemements have been demonstrated however heterostructure-based assemblies, combining eletrically condutive and dieletric textiles such as all-textile capacitors are currently missing. Here we demonstrate a superhydrophobic conducting fabric with a sheet resistance ~2.16 kΩ □-1, and a pinhole-free dielectric fabric with a relative permittivity εr ~ 2.35 enabled by graphene and hexagonal boron nitride inks, respectively. The different fabrics are then integrated to engineer the first example of an all-textile-based capacitive heterostructure with an effective capacitance ~ 26 pF cm-2 and flexibility down to at least 1 cm bending radius. The capacitor sustains 20 cylces of repeated washing and more than 100 cycles of repeated bending. Finally, an AC low-pass filter with cutoff frequency ~ 15 kHz is integrated by combining the conductive polyester and the capacitor.These results pave the way toward all-textile vertically integrated electronic devices.

  • Journal article
    Taale M, Schütt F, Carey T, Marx J, Mishra YK, Stock N, Fiedler B, Torrisi F, Adelung R, Selhuber-Unkel Cet al., 2019,

    Biomimetic carbon fiber systems engineering: a modular design strategy to generate biofunctional Composites from Graphene and Carbon Nanofibers

    , ACS Applied Materials and Interfaces, Vol: 11, Pages: 5325-5335, ISSN: 1944-8244

    Carbon-based fibrous scaffolds are highly attractive for all biomaterial applications that require electrical conductivity. It is additionally advantageous if such materials resembled the structural and biochemical features of the natural extracellular environment. Here, we show a novel modular design strategy to engineer biomimetic carbon fiber-based scaffolds. Highly porous ceramic zinc oxide (ZnO) microstructures serve as three-dimensional (3D) sacrificial templates and are infiltrated with carbon nanotubes (CNTs) or graphene dispersions. Once the CNTs and graphene coat the ZnO template, the ZnO is either removed by hydrolysis or converted into carbon by chemical vapor deposition. The resulting 3D carbon scaffolds are both hierarchically ordered and free-standing. The properties of the microfibrous scaffolds were tailored with a high porosity (up to 93%), a high Young's modulus (ca. 0.027-22 MPa), and an electrical conductivity of ca. 0.1-330 S/m, as well as different surface compositions. Cell viability, fibroblast proliferation rate and protein adsorption rate assays have shown that the generated scaffolds are biocompatible and have a high protein adsorption capacity (up to 77.32 ± 6.95 mg/cm3) so that they are able to resemble the extracellular matrix not only structurally but also biochemically. The scaffolds also allow for the successful growth and adhesion of fibroblast cells, showing that we provide a novel, highly scalable modular design strategy to generate biocompatible carbon fiber systems that mimic the extracellular matrix with the additional feature of conductivity.

  • Journal article
    Torrisi F, Carey T, 2018,

    Graphene, related two-dimensional crystals, and hybrid systems for printed and wearable electronics

    , Nano Today, Vol: 23, Pages: 73-96, ISSN: 1748-0132

    Graphene and related two-dimensional crystals and hybrid systems showcase several key properties that can address emerging needs in the ever growing markets of printed, flexible and wearable electronic devices. Graphene's flexibility, large surface area, and chemical stability, combined with its excellent electrical and thermal conductivity, make it promising as a printed flexible electrodes in flexible and wearable electronic devices. Chemically functionalized graphene and self-assembly of graphene-organic molecule composites can also improve mobility and conductivity of organic semiconducting thin film transistors (TFT). Two-dimensional crystals and hybrid systems provide optical and electrical properties complementary to those of graphene, enabling the realization of printed an flexible ultrathin-film photodetectors or photovoltaic systems. Here, we review the use of graphene and related materials for printed and wearable electronics, defining the roadmap for future applications in these areas.

  • Book chapter
    Torrisi F, Carey T, 2018,

    Printing 2D Materials

    , Publisher: Wiley, Pages: 131-205
  • Journal article
    Micallef FG, Shrestha PK, Chu D, McEwan K, Rughoobur G, Carey T, Coburn N, Torrisi F, Txoperena O, Zurutuza Aet al., 2018,

    Transparent conductors for Mid-infrared liquid crystal spatial light modulators

    , Thin Solid Films, Vol: 660, Pages: 411-420, ISSN: 0040-6090

    Transparent conductors (TCs) are required for liquid crystal spatial light modulators (LC-SLMs) in order to set up an electric field across the LC layer. In the middle infrared (Mid-IR) range (λ = 2 to 5 μm), LC-SLMs can offer a low-cost, non-mechanical, random-access and compact alternative to the gimbaled mirrors used currently for Mid-IR laser beam-steering. Indium tin oxide (ITO) is the industry standard for applications in the visible spectrum but it performs poorly in the IR, with a transmittance <20% for Mid-IR wavelengths. Little work has been done to develop a comparable material which fulfils the required properties in the Mid-IR: A sheet resistance allowing operation at typical frequencies (≈1 kHz) and, if patterned, with minimal voltage drop along the electrode, a transmittance >50% in the target range, chemical, thermal and mechanical robustness which can endure subsequent processing, and ability to be patterned at low-cost to a resolution comparable to the wavelengths investigated. Ni and Cu ultra thin metallic films (UTMFs), CuxO thin films (TFs), and chemical vapour deposition (CVD) grown mono-layer graphene were investigated. Ni UTMFs and graphene were found to have the best performance with sheet resistance values of 747±86Ω/□ and 360±34Ω/□ respectively for samples having a transmittance of 65% and 97% at λ = 2.3 μm. Both Ni UTMFs and CVD mono-layer graphene were found to be suitably stable with age. An increase of sheet resistance after baking was recorded due to oxidation and desorption of contaminating dopants respectively. Ni UTMFs were found to be patternable down to a 3 μm resolution, limited by the mask, using a standard photo-lithographic lift-off process. Transmissive LC cells with a maximum phase shift of 3π at λ = 2.3 μm were assembled with both Ni UTMFs and mono-layer graphene as TCs on sapphire, with the former having transmittance of 18.7% and contrast ratio of

  • Conference paper
    Viti L, Bianchi V, Carey T, Li L, Linfield EH, Davies AG, Tredicucci A, Yoon D, Karagiannidis PG, Lombardi Let al., 2018,

    Graphene Saturable Absorbers at Terahertz Frequency from Liquid Phase Exfoliation of Graphite

    © 2018 OSA. We report on the development of terahertz (THz) saturable-absorbers exploiting printable graphene inks. The achieved 80% transparency modulation at 3.5 THz makes these devices potential candidates as passive components for THz solid-state lasers.

  • Journal article
    Carey T, Jones C, Le Moal F, Deganello D, Torrisi Fet al., 2018,

    Spray-coating thin films on three-dimensional surfaces for a semitransparent capacitive-touch device

    , ACS Applied Materials and Interfaces, Vol: 10, Pages: 19948-19956, ISSN: 1944-8244

    Here, we formulate low surface tension (∼30 mN/m) and low boiling point (∼79 °C) inks of graphene, single-wall carbon nanotubes and conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and demonstrate their viability for spray-coating of morphologically uniform ( Sq ≈ 48 ± 3 nm), transparent conducting films (TCFs) at room temperature (∼20 °C), which conform to three dimensional curved surfaces. Large area (∼750 cm2) hybrid PEDOT:PSS/graphene films achieved an optical transmission of 67% in the UV and 64% in the near-infrared wavelengths with a conductivity of ∼104 S/m. Finally, we demonstrate the spray-coating of TCFs as an electrode on the inside of a poly(methyl methacrylate) sphere, enabling a semitransparent (around 360°) and spherical touch sensor for interactive devices.

  • Conference paper
    Viti L, Bianchi V, Carey T, Li L, Linfield EH, Davies AG, Tredicucci A, Yoon D, Karagiannidis PG, Lombardi L, Tomarchio F, Ferrari AC, Torrisi F, Vitiello MSet al., 2018,

    Graphene saturable absorbers at terahertz frequency from liquid phase exfoliation of graphite

    © OSA 2018. We report on the development of terahertz (THz) saturable-absorbers exploiting printable graphene inks. The achieved 80% transparency modulation at 3.5 THz makes these devices potential candidates as passive components for THz solid-state lasers.

  • Journal article
    Call TP, Carey T, Bombelli P, Lea-Smith DJ, Hooper P, Howe CJ, Torrisi Fet al., 2017,

    Platinum-free, graphene based anodes and air cathodes for single chamber microbial fuel cells

    , Journal of Materials Chemistry A, Vol: 5, Pages: 23872-23886, ISSN: 2050-7496

    Microbial fuel cells (MFCs) exploit the ability of microorganisms to generate electrical power during metabolism of substrates. However, the low efficiency of extracellular electron transfer from cells to the anode and the use of expensive rare metals as catalysts, such as platinum, limit their application and scalability. In this study we investigate the use of pristine graphene based electrodes at both the anode and the cathode of a MFC for efficient electrical energy production from the metabolically versatile bacterium Rhodopseudomonas palustris CGA009. We achieve a volumetric peak power output (PV) of up to 3.51 ± 0.50 W m-3 using graphene based aerogel anodes with a surface area of 8.2 m2 g-1. We demonstrate that enhanced MFC output arises from the interplay of the improved surface area, enhanced conductivity, and catalytic surface groups of the graphene based electrode. In addition, we show a 500-fold increase in PV to 1.3 ± 0.23 W m-3 when using a graphene coated stainless steel (SS) air cathode, compared to an uncoated SS cathode, demonstrating the feasibility of a platinum-free, graphene catalysed MFCs. Finally, we show a direct application for microwatt-consuming electronics by connecting several of these coin sized devices in series to power a digital clock.

  • Journal article
    Carey T, Cacovich S, Divitini G, Ren J, Mansouri A, Kim JM, Wang C, Ducati C, Sordan R, Torrisi Fet al., 2017,

    Fully inkjet-printed two-dimensional material field-effect heterojunctions for wearable and textile electronics

    , Nature Communications, Vol: 8, Pages: 1-11, ISSN: 2041-1723

    Fully printed wearable electronics based on two-dimensional (2D) material heterojunction structures also known as heterostructures, such as field-effect transistors, require robust and reproducible printed multi-layer stacks consisting of active channel, dielectric and conductive contact layers. Solution processing of graphite and other layered materials provides low-cost inks enabling printed electronic devices, for example by inkjet printing. However, the limited quality of the 2D-material inks, the complexity of the layered arrangement, and the lack of a dielectric 2D-material ink able to operate at room temperature, under strain and after several washing cycles has impeded the fabrication of electronic devices on textile with fully printed 2D heterostructures. Here we demonstrate fully inkjet-printed 2D-material active heterostructures with graphene and hexagonal-boron nitride (h-BN) inks, and use them to fabricate all inkjet-printed flexible and washable field-effect transistors on textile, reaching a field-effect mobility of ~91 cm2 V-1 s-1, at low voltage (<5 V). This enables fully inkjet-printed electronic circuits, such as reprogrammable volatile memory cells, complementary inverters and OR logic gates.

  • Journal article
    Carey T, Cacovich S, Divitini G, Ren J, Mansouri A, Kim J, Wang C, Ducati C, Sordan R, Torrisi Fet al., 2017,

    Fully inkjet printed 2d material field effect heterostructures for wearable and textile electronics

    , Nature Communications

    Fully-printed electronics based on two-dimensional (2d) material heterostructures, such as field effect transistors, require robust and reproducible printed multi-layer stacks consisting of active channel, dielectric and conductive contact layers. Solution processing of graphite and other layered materials provides low-cost inks enabling printed electronic devices, for example by inkjet printing. However, the limited quality of the 2d material inks, the complexity of the layered arrangement for fully inkjet printed field effect heterostructures operating at room temperature and pressure, and the lack of a suitable dielectric 2d ink has impeded the fabrication of active field effect devices with fullyprinted 2d heterostructures. Moreover, electronic devices on textile (i.e. textile electronics) operate over a long time at room temperature, under strain and after several washing cycles. Exploiting the properties of inkjet printed electronics based on 2d materials for wearable and textile electronics requires robust, stable and washable printed devices. Here we demonstrate fully inkjet printed 2d material active heterostructures using graphene and hexagonal-boron nitride (h-BN) inks, and use them to fabricate all inkjet printed flexible and washable field effect transistors (FETs) on textile, reaching a field effect mobility of μ ~ 91 ± 29 cm2 V-1 s -1 on polyester fabric, at low operating voltages (< 5 V). The devices maintained their performance even under ∼ 4% strain and showed stable operation for periods up to 2 years, indicating the two-fold role of the h-BN layer as a flexible dielectric and encapsulant. Our graphene/h-BN FETs are washable up to 20 cycles, which is ideal for textile electronics. The viability of our process for printed and textile electronics is demonstrated by fully inkjet printing electronic circuits, such as reprogrammable volatile memory cells, complementary inverters, and OR logic gates with graphene/h-BN FETs.

  • Journal article
    Bianchi V, Carey T, Viti L, Li L, Linfield EH, Davies AG, Tredicucci A, Yoon D, Karagiannidis PG, Lombardi Let al., 2017,

    Terahertz saturable absorbers from liquid phase exfoliation of graphite

    , Nature Communications, Vol: 8, ISSN: 2041-1723

    Saturable absorbers (SA) operating at terahertz (THz) frequencies can open new frontiers in the development of passively mode-locked THz micro-sources. Here we report the fabrication of THz SAs by transfer coating and inkjet printing single and few-layer graphene films prepared by liquid phase exfoliation of graphite. Open-aperture z-scan measurements with a 3.5 THz quantum cascade laser show a transparency modulation ∼80%, almost one order of magnitude larger than that reported to date at THz frequencies. Fourier-transform infrared spectroscopy provides evidence of intraband-controlled absorption bleaching. These results pave the way to the integration of graphene-based SA with electrically pumped THz semiconductor micro-sources, with prospects for applications where excitation of specific transitions on short time scales is essential, such as time-of-flight tomography, coherent manipulation of quantum systems, time-resolved spectroscopy of gases, complex molecules and cold samples and ultra-high speed communications, providing unprecedented compactness and resolution.

  • Journal article
    Popa D, Jiang Z, Bonacchini GE, Zhao Z, Lombardi L, Torrisi F, Ott AK, Lidorikis E, Ferrari ACet al., 2017,

    A stable, power scaling, graphene-mode-locked all-fiber oscillator

    , Applied Physics Letters, Vol: 110, ISSN: 1077-3118

    We report power tunability in a fiber laser mode-locked with a solution-processed filtered graphene film on a fiber connector. ∼370 fs pulses are generated with output power continuously tunable from ∼4 up to ∼52 mW. This is a simple, low-cost, compact, portable, all-fiber ultrafast source for applications requiring environmentally stable, portable sources, such as imaging.

  • Journal article
    Karagiannidis PG, Hodge SA, Lombardi L, Tomarchio F, Decorde N, Milana S, Goykhman I, Su Y, Mesite SV, Johnstone DN, Leary RK, Midgley PA, Pugno NM, Torrisi F, Ferrari ACet al., 2017,

    Microfluidization of graphite and formulation of graphene-based conductive inks

    , ACS Nano, Vol: 11, Pages: 2742-2755, ISSN: 1936-0851

    We report the exfoliation of graphite in aqueous solutions under high shear rate [∼ 108 s-1] turbulent flow conditions, with a 100% exfoliation yield. The material is stabilized without centrifugation at concentrations up to 100 g/L using carboxymethylcellulose sodium salt to formulate conductive printable inks. The sheet resistance of blade coated films is below ∼2Ω/□. This is a simple and scalable production route for conductive inks for large-area printing in flexible electronics.

  • Journal article
    Ren J, Wang C, Zhang X, Carey T, Chen K, Yin Y, Torrisi Fet al., 2017,

    Environmentally-friendly conductive cotton fabric as flexible strain sensor based on hot press reduced graphene oxide

    , Carbon, Vol: 111, Pages: 622-630, ISSN: 0008-6223

    A flexible conductive cotton fabric was demonstrated by formulation and deposition of a graphene oxide (GO) dispersion onto a cotton fabric by vacuum filtration. The deposited GO amount was controlled by the concentration and volume of the GO dispersion. The GO was reduced by a hot press method at 180 °C for 60 min, and no chemical reductant was needed in both the deposition and reduction processes. The carbon-oxygen ratio increased from 1.77 to 3.72 after the hot press reduction. The as-prepared flexible conductive cotton fabric showed a sheet resistance as low as 0.9 kΩ/sq. The sheet resistance of the conductive cotton fabric only increased from ∼0.9 kΩ/sq to ∼1.2 kΩ/sq after 10 washing cycles, exhibiting good washability. The conductive cotton fabric showed viability as a strain sensor even after 400 bending cycles, in which the stable change in the electrical resistance went from ∼3500 kΩ under tensile strain to ∼10 kΩ under compressive strain. This cost-effective and environmentally-friendly method can be easily extended to scalable production of reduced GO based flexible conductive cotton fabrics.

  • Journal article
    Capelli E, Torrisi F, Venturini L, Granato M, Fassina L, Lupo GFD, Ricevuti Get al., 2017,

    Low-Frequency Pulsed Electromagnetic Field Is Able to Modulate miRNAs in an Experimental Cell Model of Alzheimer's Disease

    , JOURNAL OF HEALTHCARE ENGINEERING, Vol: 2017, ISSN: 2040-2295
  • Journal article
    Borg RM, Fenech Salerno B, Vassallo N, Bordonne R, Cauchi RJet al., 2016,

    Disruption of snRNP biogenesis factors Tgs1 and pICln induces phenotypes that mirror aspects of SMN-Gemins complex perturbation in Drosophila, providing new insights into spinal muscular atrophy

    , Neurobiology of Disease, Vol: 94, Pages: 245-258, ISSN: 0969-9961

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