Nanowerk July 27, 2021 OLED pixels normally consist of multiple layers which ensure, for example, that electrons can travel in the pixel with as little resistance as possible. The fine-tuning of the layer properties, for example, electron mobility or the emitted wavelength (color of the light), is a complex task. An international team of researchers (South Korea, Ukraine, Belgium, Germany) compared a wide range of computer-simulated and experimentally measured properties of OLED thin films, trying to understand whether OLED design can be guided solely by computer. They established a molecular library of typical OLED materials to streamline the design of […]
Tag Archives: Advanced materials
Through the thin-film glass, researchers spot a new liquid phase
Phys.org July 27, 2021 The structure of a glass closely resembles the liquid phase, but its properties are like solids, akin to a crystal. In vapor deposition, a material is changed from a gas into a solid directly. Researchers at the University of Pennsylvania used vapor deposition to create very dense thin-film glasses, corresponding to the packing of the new liquid phase, with a density much higher than was predicted to be possible without applying immense amounts of pressure. Thin films of these glasses can have density values even higher than crystal. Detailed structural information analysis of how individual molecules […]
Achilles heel of graphene exposed
Nanowerk July 19, 2021 The quantum Hall effect is the seminal example of topological protection as charge carriers are transmitted through one-dimensional edge channels where backscattering is prohibited. In conventional Hall bar geometries, topological protection of graphene edge channels is found less robust than in high mobility semi-conductors. An international team of researchers (Belgium, Germany, Japan) exploring graphene quantum Hall regime at the local scale revealed that the detrimental influence of antidots along the graphene edges, mediating backscattering towards upstream edge channels triggering topological breakdown. The finding is a major step forward in the understanding of the quantum Hall effect […]
Future information technologies: Topological materials for ultrafast spintronics
Phys.org July 16, 2021 To understand how fast excited electrons in the bulk and on the surface of Sb react to the external energy input, and to explore the mechanisms governing their response an international team of researchers (Germany, Russia, Ireland) used time-, spin- and angle-resolved photoemission to femtosecond-laser excitation. The data showed a ‘kink’ structure in transiently occupied energy-momentum dispersion of surface states, which can be interpreted as an increase in effective electron mass. They were able to show that this mass enhancement plays a decisive role in determining the complex interplay in the dynamical behaviors of electrons from […]
Harnessing the dark side
Nanowerk July 13, 2021 Optical singularities, which appear completely dark, typically occur when the phase of light with a specific wavelength, or color, is undefined. Researchers at Harvard University have developed a new way to control and shape optical singularities. The metasurface tilts the wavefront of light in a very precise manner over a surface so that the interference pattern of the transmitted light produces extended regions of darkness. Their approach allows precise engineering of dark regions with remarkably high contrast. Engineered singularities could be used to trap atoms in dark regions and improve super high-resolution imaging. As darkness has […]
New ‘Metafabric’ Passively Cools The Human Body by Almost 5 Degrees Celsius
Science Alert July 13, 2021 The metafabric developed by researchers in China uses titanium oxide-polylactic acid composite nanoparticles laminated with a thin layer of polytetrafluoroethylene (PTFE). It is designed to strongly reflect visible light (VIS), mid-infrared (MIR) and ultraviolet (UV) ranges. The wide distribution of nanoparticles, when combined with PTFE nanobeads, provides broad-spectrum scattering and reflectivity across the UV-VIS-NIR band. They tested the material in clear sky conditions measuring the temperature of the fabric in comparison to other common materials lying on a panel. Under peak solar irradiance between 11:00 and 15:00, the temperature of the metafabric was approximately 5.0°, […]
Mosquito-resistant clothing prevents bites in trials
Phys.org July 13, 2021 An international team of researchers (USA – North Carolina State University, Germany) has developed a mathematical model for fabric barriers that resist bites from Aedes aegypti mosquitoes based on textile physical structure and no insecticides. The model was derived from mosquito morphometrics and analysis of mosquito biting behavior. Woven filter fabrics, precision polypropylene plates, and knitted fabrics were used for model validation. Based on the model predictions, prototype knitted textiles and garments were developed that prevented mosquito biting, and comfort testing showed the garments to possess superior thermophysiological properties. The fabrics provided a three-times greater bite […]
Graphene additive manufacturing for flexible and printable electronics
Phys.org July 2, 2021 As a proof-of-concept researchers at Kansas State University used graphene aerosol gel ink, synthesized via an energy efficient, catalyst-free, and nonhazardous chemical precursor detonation method, such as hydrocarbons (e.g., acetylene) in the presence of controlled oxygen. They used the ink to print microsupercapacitors in interdigitated electrodes (IDEs) geometry on 25-μm thick polyimide substrates using a micro plotter. The microsupercapacitors showed an aerial capacitance of 55 μF/cm2 and volumetric capacitance of 3.25 F/cm3 at a current density of 6.0 microamp/cm2 and 20 milliamp/cm3, respectively. The printed devices did not show a significant distortion in the cyclic voltammetry […]
The pressure is off and high temperature superconductivity remains
Phys.org July 8, 2021 The grand challenge in superconductivity research and development is no longer restricted to further increasing the superconducting transition temperature under extreme conditions and must now include concentrated efforts to lower, and better yet remove, the applied pressure required. An international team of researchers (USA – Houston University, Rice University, China) has shown such a possibility in the pure and doped high-temperature superconductor FeSe by retaining, at ambient pressure via pressure quenching, its Tc up to 37 K and other pressure-induced phases. They observed that some phases remain stable without pressure at up to 300 K and […]
Optical superoscillation without side waves
EurekAlert June 24, 2021 Optical superoscillation refers to a phenomenon of a wave packet that can oscillate locally faster than its highest Fourier component, which potentially produces an extremely localized wave in the far field. It provides an alternative way to overcome the diffraction limit and improve the resolution of an optical microscopy system. However, the optical superoscillatory waves are inevitably accompanied by strong side lobes, which limits their fields of view and, hence, potential applications. Researchers in China report both experimentally and theoretically a new superoscillatory wave form, which not only produces significant feature size down to deep subwavelength, […]