Science Daily May 15, 2024 Chemical doping is an important approach to manipulating charge-carrier concentration and transport in organic semiconductors (OSCs) and it ultimately enhances device performance. However, conventional doping strategies often rely on the use of highly reactive dopants which are consumed during the doping process. Achieving efficient doping with weak and/or widely accessible dopants under mild conditions remains a considerable challenge. An international team of researchers (Sweden, Italy, South Korea, UK, Italy, USA – Georgia Institute of Technology) showed that a previously undescribed concept for the photocatalytic doping of OSCs that used air as a weak oxidant (p-dopant) […]
Category Archives: Materials science
Scientists create black arsenic visible infrared photodetectors
Phys.org May 8, 2024 Black arsenic as 2-dimensional van der Waals layered material is a promising candidate for electronic and photonic applications because of tunable bandgap layers, high carrier mobility, and anisotropic transport feature. However, the potential of black arsenic for engineering nanophotoelectronic devices in the range from visible to near-infrared wavelength has not been reported. Researchers in China used black arsenic in visible–infrared detectors at the range from 520 to 1,550 nm, exhibiting a photoresponsivity of 0.4 A·W−1 and a detective of 1.37 × 108 Jones… read more. Open Access TECHNICAL ARTICLE
Thermoelectric materials approach boosts band convergence to avoid time-consuming trial-and-error approach
Phys.org May 16, 2024 Electronic band convergence can have a beneficial impact on thermoelectric performance, but finding the right band-converged compositions is still time-consuming. A team of researchers in the US (University of Houston, Rice University) proposed a method for designing a series of compositions with simultaneous band convergence in the high-entropy YbxCa1−xMgyZn2−ySb2 material by zeroing the weighted sum of crystal-field splitting energies of the parent compounds. They found that such compositions have both larger power factors and lower thermal conductivities and that one of them exhibited a large thermoelectric figure of merit value in comparison with to other p-type […]
Innovative electrospinning method creates advanced ceramic nanofibers and springs
Nanowerk May 9, 2024 Electrospinning has been applied to produce ceramic fibers using sol gel-based spinning solutions consisting of ceramic precursors, a solvent, and a polymer to control the viscosity of the solution. However, the addition of polymers to the spinning solution makes the process more complex, increases the processing time, and results in porous mechanically weak ceramic fibers. Researchers in the UK developed a coelectrospinning technique, where a nonspinnable sol consisting of only the ceramic precursor(s) and solvent(s) was encapsulated inside a polymeric shell, forming core–shell precursor fibers that were further calcined into ceramic fibers with reduced porosity, decreased […]
Transforming common soft magnets into a next-generation thermoelectric conversion materials by 3 minutes heat treatment
Science Daily May 9, 2024 Nernst effect, a promising transverse thermoelectric phenomenon for energy harvesting and heat sensing, has been challenging to utilize due to the scarcity of materials with large anomalous Nernst coefficients. Researchers in Japan have shown how nanostructure engineering enables transforming simple magnetic alloys into spin-caloritronic materials displaying significantly large transverse thermoelectric conversion properties. They demonstrated a remarkable ~ 70% improvement in the anomalous Nernst coefficients and a significant enhancement in the power factor in flexible Fe-based amorphous materials by nanostructure engineering without changing their composition. This surpassed all reported amorphous alloys and was comparable to single crystals showing large […]
Research team discovers new property of light
Phys.org May 7, 2024 The nature of enhanced photoemission in disordered and amorphous solids is an intriguing question. An international team of researchers (Russia, USA – UC Irvine) studied structural photoemission in heterogeneous cross-linked silicon glass, a material that represents an intermediate state between the amorphous and crystalline phases, characterized by a narrow distribution of structure sizes. The model system showed a clear dependence of photoemission on size and disorder across a broad range of energies. While phonon-assisted indirect optical transitions are insufficient to describe observable emissions, their experiments suggested these could be understood through electronic Raman scattering. They attributed […]
When does a conductor not conduct?
Science Daily April 29, 2024 Flat bands in 2D and layered materials with a kagome lattice enhance electronic correlations. Although theoretically predicted, correlated-electron Mott insulating phases in monolayer 2D MOFs with a kagome structure have not yet been realized experimentally. An international team of researchers (Australia, Japan) synthesised a 2D kagome MOF on a 2D insulator. It revealed a MOF electronic energy gap of ∼200 meV, consistent with dynamical mean-field theory predictions of a Mott insulator. Combining template-induced and STM probe-induced gating, they locally tuned the electron population of the MOF kagome bands and induced Mott MITs. According to the researchers their […]
When injecting pure spin into chiral materials, direction matters
Science Daily May 3, 2024 The chiral induced spin selectivity (CISS) effect is emerging as a design principle for creating next-generation spintronic devices. CISS implies that the spin preference of chiral structures persists upon injection of pure spin currents and can act as a spin analyzer without the need for a ferromagnet. A team of researchers (North Carolina State University, University of Pittsburgh, University of Illinois – Urbana) showed that an anomalous spin current absorption in chiral metal oxides that manifested a colossal anisotropic nonlocal Gilbert damping with a maximum-to-minimum ratio of up to 1000%. A twofold symmetry of the […]
Researchers control quantum properties of 2D materials with tailored light
Phys.org April 15, 2024 The stacking and twisting of atom-thin structures with matching crystal symmetry has provided a unique way to create new superlattice structures in which new properties emerge. An international team of researchers (Germany, Spain, USA – SLAC National Accelerator Laboratory, Stanford University) demonstrated a tailored light-wave-driven analogue to twisted layer stacking. Tailoring the spatial symmetry of the light waveform to that of the lattice of a hexagonal boron nitride monolayer and then twisting this waveform resulted in optical control of time-reversal symmetry breaking and the realization of the topological Haldane model in a laser-dressed two-dimensional insulating crystal. […]
‘Surprising’ hidden activity of semiconductor material spotted by researchers
Science Daily April 11, 2024 Studies of electric field-driven insulator-to-metal (IMT) in the prototypical vanadium dioxide (VO2) thin-film channel devices are largely focused on the electrical and elastic responses of the films, but the response of the corresponding Titanium dioxide (TiO2) substrate is often overlooked. An international team of researchers (USA – Pennsylvania State University, Cornell University, Argonne National Laboratory, Germany) found that in-operando spatiotemporal imaging of the coupled elastodynamics using X-ray diffraction microscopy of a VO2 film channel device on TiO2 substrate the film channel bulged during the IMT instead shrinking as expected. A micron thick proximal layer in […]