Nanowerk May 30, 2020 Intrinsically stretchable optoelectronic devices such as light-emitting capacitors usually require high driving alternating voltages and excitation frequencies to achieve sufficient luminance in ambient lighting conditions. To lower the electronic operating conditions an international team of researchers (Singapore, USA – Cornell University) developed a material made up of unique blend of fluoroelastomer and surfactant. It has very high dielectric permittivity and self-healing properties, transparent, and elastic. A healable, low-field illuminating optoelectronic stretchable (HELIOS) device can turn on at voltages that are four times lower and achieve illumination that is more than 20 times brighter. Due to the […]
Tag Archives: Advanced materials
Designing a flexible material to protect buildings, military personnel
Phys.org May 27, 2020 Cloaking materials are mature because the properties of acoustic (radar, sonar) and optical waves (infrared) are well-understood. However, cloaking for elastic waves in solid media is lagging. A team of researchers in the US (University of Missouri, MIT) has designed and fabricated a new class of cloaking materials which is composed of a functionally graded lattice embedded in an isotropic continuum background. The layers were 3-D printed and manually assembled. They experimentally and numerically investigated the characteristics of the proposed cloak and found very good cloaking performance under both tension and shear loadings. Potential applications for […]
Researchers breaking new ground in materials science
Science Daily May 20, 2020 An international team of researchers (Canada, Italy) demonstrated the fabrication of mesoscale ordered two-dimensional π-conjugated polymer kagome lattices with semiconducting properties. To make the material they combined a rigid azatriangulene precursor and a hot dosing approach, which favours molecular diffusion and eliminates voids in the network. These results open opportunities for the synthesis of two-dimensional π-conjugated polymer Dirac cone materials and their integration into devices. The integration of this system into a device (e.g. transistors) may lead to outstanding performances. The results will foster more studies on a wide range of two-dimensional conjugated polymers with […]
Chameleon materials: The origin of color variation in low-dimensional perovskites
Phys.org May 11, 2020 Perovskites ability to emit light over a broad wavelength range is widely attributed to broad luminescence with a large Stokes shift to self-trapped excitons forming due to strong carrier–phonon interactions. Researchers in the Netherlands highlight the extrinsic origin of their broad band emission. As shown by below-gap excitation, in-gap states in the crystal bulk are responsible for the broad emission. This insight advances the understanding of the emission properties of low-dimensional perovskites and question the generality of the attribution of broad band emission in metal halide perovskite and related compounds to self-trapped excitons…read more. Open Access […]
Making Materials Mimic Each Other
American Physical Society May 6, 2020 Based on the 2017 research confirming that spectral mimicry is theoretically possible, an international team of researchers (USA – Tulane University, US Army Research Laboratory, UMass Boston, Louisiana State University, UK) proposed a new way to make one material behave like another by applying specially designed time-dependent fields such as laser pulse. They derived a field-free, nonlinear equation of motion for controlling the expectation value of an essentially arbitrary observable together with rigorous constraints that determine the limits of controllability. They discuss the experimental feasibility of implementing the control fields generated by this model…read […]
Dirty carbon reveals a sophisticated side
MIT News April 27, 2020 Polycyclic heavy hydrocarbons (HHs) such as coal, tar, and pitch are a family of materials with extremely rich and complex chemistry, representing a massive opportunity for their use in a range of potential applications. An international team of researchers (USA – MIT, industry, Canada, China) shows that optimal selection of initial HHs based on molecular constituents is essential in tuning the material for a particular and targeted electronic application. Combining the selection of feedstock chemistry (H:C and aromatic content) and controlling variable laser treatment parameters (laser power, speed, and focus) lead to full control over […]
Engineers make a promising material stable enough for use in solar cells
Science Daily April 29, 2020 Inherently soft crystal lattice of Halide perovskites allows greater tolerance to lattice mismatch, making them promising for heterostructure formation and semiconductor integration. However, their high intrinsic ion mobility, which leads to interdiffusion and large junction widths and their poor chemical stability, epitaxial growth of atomically sharp heterostructures of halide perovskites has not yet been achieved. An international team of researchers (USA – Perdue University, MIT, UC Berkeley, Lawrence Berkeley National Laboratory, China) has developed a strategy to substantially inhibit in-plane ion diffusion in two-dimensional halide perovskites by incorporating rigid π-conjugated organic ligands. They have demonstrated […]
Unlocking promising properties to create future technologies
EurekAlert April 30, 2020 The manifestation of quantization in macroscopic physical systems has showcased important quantum phenomena, such as quantized conductance in (fractional) quantum Hall effects and quantized vortices in superconductors. An international team of researchers (USA – Rensselaer Polytechnic Institute, Florida State University, UT Dallas, Arizona State University, Japan, Hong Kong) reported the experimental observation of quantized exciton energies in a macroscopic system with strong Coulomb interaction, monolayer WSe2 crystal under a strong magnetic field. This work demonstrates the optical version of the QHE for excitons, and the researchers believe it will open the door for further discovery and […]
Wide-band-gap semiconductors could harvest sunlight underwater
Physics World April 17, 2020 Using detailed-balance calculations researchers at the University of New York have shown that underwater solar cells can exhibit efficiencies from ∼55% in shallow waters to more than 65% in deep waters, while maintaining a power density >5 mW cm −2. They showed that the optimum band gap of the solar cell shifts by ∼0.6 eV between shallow and deep waters and plateaus at ∼2.1 eV at intermediate depths, independent of geographical location. This wide range in optimum band-gap energies opens the potential for a library of wide-band-gap semiconductors to be used for high-efficiency underwater solar […]
New textile could keep you cool in the heat, warm in the cold
Phys.org April 1, 2020 Researchers in China freeze-spun silk and chitosan, a material from the hard outer skeleton of shellfish, into colored fibers with porous microstructures. They filled the pores with polyethylene glycol (PEG), a phase-changing polymer that absorbs and releases thermal energy. The threads were coated with polydimethylsiloxane to keep the liquid PEG from leaking out. The resulting fibers were strong, flexible, and water-repellent. To test the fibers, the researchers wove them into a patch of fabric and put inside a polyester glove. When a person wearing the glove placed their hand in a hot chamber (122°F), the solid […]