394 research outputs found
Water-based and Biocompatible 2D Crystal Inks: from Ink Formulation to All- Inkjet Printed Heterostructures
Fully exploiting the properties of 2D crystals requires a mass production
method able to produce heterostructures of arbitrary complexity on any
substrate, including plastic. Solution processing of graphene allows simple and
low-cost techniques such as inkjet printing to be used for device fabrication.
However, available inkjet printable formulations are still far from ideal as
they are either based on toxic solvents, have low concentration, or require
time-consuming and expensive formulation processing. In addition, none of those
formulations are suitable for thin-film heterostructure fabrication due to the
re-mixing of different 2D crystals, giving rise to uncontrolled interfaces,
which results in poor device performance and lack of reproducibility. In this
work we show a general formulation engineering approach to achieve highly
concentrated, and inkjet printable water-based 2D crystal formulations, which
also provides optimal film formation for multi-stack fabrication. We show
examples of all-inkjet printed heterostructures, such as large area arrays of
photosensors on plastic and paper and programmable logic memory devices, fully
exploiting the design flexibility of inkjet printing. Finally, dose-escalation
cytotoxicity assays in vitro also confirm the inks biocompatible character,
revealing the possibility of extending use of such 2D crystal formulations to
drug delivery and biomedical applications
Heterostructures produced from nanosheet-based inks.
The new paradigm of heterostructures based on two-dimensional (2D) atomic crystals has already led to the observation of exciting physical phenomena and creation of novel devices. The possibility of combining layers of different 2D materials in one stack allows unprecedented control over the electronic and optical properties of the resulting material. Still, the current method of mechanical transfer of individual 2D crystals, though allowing exceptional control over the quality of such structures and interfaces, is not scalable. Here we show that such heterostructures can be assembled from chemically exfoliated 2D crystals, allowing for low-cost and scalable methods to be used in device fabrication.This work was supported by The Royal Society, U.S. Army, European Science Foundation (ESF) under the EUROCORES Programme EuroGRAPHENE (GOSPEL), European Research Council, and EC under the Graphene Flagship (contract no. CNECT-ICT-604391). Y.-J.K.’s work was supported by the Global Research Laboratory (GRL) Program (2011-0021972) of the Ministry of Education, Science and Technology, Korea. F.W. acknowledges support from the Royal Academy of Engineering; A.F. is a FRS-FNRS Research Fellow
Fully inkjet-printed two-dimensional material field-effect heterojunctions for wearable and textile electronics.
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
Heterostructures produced from nanosheet-based inks
The new paradigm of heterostructures based on two-dimensional (2D) atomic
crystals has already led to the observation of exciting physical phenomena and
creation of novel devices. The possibility of combining layers of different 2D
materials in one stack allows unprecedented control over the electronic and
optical properties of the resulting material. Still, the current method of
mechanical transfer of individual 2D crystals, though allowing exceptional
control over the quality of such structures and interfaces, is not scalable.
Here we show that such heterostructures can be assembled from chemically
exfoliated 2D crystals, allowing for low-cost and scalable methods to be used
in the device fabrication
Flexible, Print-in-Place 1D-2D Thin-Film Transistors Using Aerosol Jet Printing
In this work, we overcome temperature constraints and demonstrate 1D−2D thin-film transistors (1D−2D TFTs) in a low-temperature (maximum exposure ≤80 °C) full print-in-place process (i.e., no substrate removal from printer throughout
the entire process) using an aerosol jet printer. Semiconducting 1D CNT channels are used with a 2D hexagonal boron
nitride (h-BN) gate dielectric and traces of silver nanowires as the conductive electrodes, all deposited using the same
printer. The aerosol jet-printed 2D h-BN films were realized via proper ink formulation, such as utilizing the binder
hydroxypropyl methylcellulose, which suppresses redispersion between adjacent printed layers. In addition to an ON/
OFF current ratio up to 3.5 Å~ 105, channel mobility up to 10.7 cm2·V-1·s-1, and low gate hysteresis, 1D−2D TFTs exhibit
extraordinary mechanical stability under bending due to the nanoscale network structure of each layer, with minimal
changes in performance after 1000 bending test cycles at 2.1% strain. It is also confirmed that none of the device layers
require high-temperature treatment to realize optimal performance. These findings provide an attractive approach toward
a cost-effective, direct-write realization of electronics
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