24,186 research outputs found
Logic Ciucuits Using Solution-processed Single-walled Carbon Nanotue Transistors
This letter reports on the realization of logic circuits employing
solution-processed networks of single-walled carbon nanotubes. We constructed
basic logic gates (inverter, NAND and NOR) with n- and p-type field-effect
transistors fabricated by solution-based chemical doping. Complementary
metal-oxide-semiconductor inverters exhibited voltage gains of up to 20, which
illustrates the great potential of carbon nanotube networks for printable
flexible electronics.Comment: 12 PAGES, 3 FIGURE
Device modelling for bendable piezoelectric FET-based touch sensing system
Flexible electronics is rapidly evolving towards
devices and circuits to enable numerous new applications. The
high-performance, in terms of response speed, uniformity and
reliability, remains a sticking point. The potential solutions for
high-performance related challenges bring us back to the timetested
silicon based electronics. However, the changes in the
response of silicon based devices due to bending related stresses is
a concern, especially because there are no suitable models to
predict this behavior. This also makes the circuit design a
difficult task. This paper reports advances in this direction,
through our research on bendable Piezoelectric Oxide
Semiconductor Field Effect Transistor (POSFET) based touch
sensors. The analytical model of POSFET, complimented with
Verilog-A model, is presented to describe the device behavior
under normal force in planar and stressed conditions. Further,
dynamic readout circuit compensation of POSFET devices have
been analyzed and compared with similar arrangement to reduce
the piezoresistive effect under tensile and compressive stresses.
This approach introduces a first step towards the systematic
modeling of stress induced changes in device response. This
systematic study will help realize high-performance bendable
microsystems with integrated sensors and readout circuitry on
ultra-thin chips (UTCs) needed in various applications, in
particular, the electronic skin (e-skin)
Solvent Exfoliation of Electronic-Grade, Two-Dimensional Black Phosphorus
Solution dispersions of two-dimensional (2D) black phosphorus (BP), often
referred to as phosphorene, are achieved by solvent exfoliation. These
pristine, electronic-grade BP dispersions are produced with anhydrous, organic
solvents in a sealed tip ultrasonication system, which circumvents BP
degradation that would otherwise occur via solvated oxygen or water. Among
conventional solvents, n-methyl-pyrrolidone (NMP) is found to provide stable,
highly concentrated (~0.4 mg/mL) BP dispersions. Atomic force microscopy,
scanning electron microscopy, transmission electron microscopy, Raman
spectroscopy, and X-ray photoelectron spectroscopy show that the structure and
chemistry of solvent-exfoliated BP nanosheets are comparable to mechanically
exfoliated BP flakes. Additionally, residual NMP from the liquid-phase
processing suppresses the rate of BP oxidation in ambient conditions.
Solvent-exfoliated BP nanosheet field-effect transistors (FETs) exhibit
ambipolar behavior with current on/off ratios and mobilities up to ~10000 and
~50 cm^2/(V*s), respectively. Overall, this study shows that stable, highly
concentrated, electronic-grade 2D BP dispersions can be realized by scalable
solvent exfoliation, thereby presenting opportunities for large-area,
high-performance BP device applications.Comment: 6 figures, 31 pages, including supporting informatio
Towards flexible asymmetric MSM structures using Si microwires through contact printing
This paper presents development of flexible metal-semiconductor-metal devices using silicon (Si) microwires. Monocrystalline Si in the shape of microwires are used which are developed through standard photolithography and etching. These microwires are assembled on secondary flexible substrates through a dry transfer printing by using a polydimethylsiloxane stamp. The conductive patterns on Si microwires are printed using a colloidal silver nanoparticles based solution and an organic conductor i.e. poly (3,4-ethylene dioxthiophene) doped with poly (styrene sulfonate). A custom developed spray coating technique is used for conductive patterns on Si microwires. A comparative study of the current–voltage (I–V) responses is carried out in flat and bent orientations as well as the response to the light illumination of the wires is explored. Current variations as high as 17.1 μA are recorded going from flat to bend conditions, while the highest I on/I off ratio i.e. 43.8 is achieved with light illuminations. The abrupt changes in the current response due to light-on/off conditions validates these devices for fast flexible photodetector switches. These devices are also evaluated based on transfer procedure i.e. flip-over and stamp-assisted transfer printing for manipulating Si microwires and their subsequent post-processing. These new developments were made to study the most feasible approach for transfer printing of Si microwires and to harvest their capabilities such as photodetection and several other applications in the shape of metal-semiconductor-metal structures
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Room-Temperature Sputtered SnO2 as Robust Electron Transport Layer for Air-Stable and Efficient Perovskite Solar Cells on Rigid and Flexible Substrates.
Extraordinary photovoltaic performance and intriguing optoelectronic properties of perovskite solar cells (PSCs) have aroused enormous interest from both academic research and photovoltaic (PV) industry. In order to bring PSC technology from laboratory to market, material stability, device flexibility, and scalability are important issues to address for vast production. Nevertheless, PSCs are still primarily prepared by solution methods which limit film scalability, while high-temperature processing of metal oxide electron transport layer (ETL) makes PSCs costly and incompatible with flexible substrates. Here, we demonstrate rarely-reported room-temperature radio frequency (RF) sputtered SnO2 as a promising ETL with suitable band structure, high transmittance, and excellent stability to replace its solution-processed counterpart. Power conversion efficiencies (PCEs) of 12.82% and 5.88% have been achieved on rigid glass substrate and flexible PEN substrate respectively. The former device retained 93% of its initial PCE after 192-hour exposure in dry air while the latter device maintained over 90% of its initial PCE after 100 consecutive bending cycles. The result is a solid stepping stone toward future PSC all-vapor-deposition fabrication which is being widely used in the PV industry now
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