MRS Bulletin Materials News Podcast

In this podcast episode, MRS Bulletin’s Sophia Chen interviews Michael Dickey of North Carolina State University about the discovery and mechanical properties of glassy gels. Dicky credits his postdoc Meixiang Wang who, while studying ionic liquids, created the first glassy gel. Dicky’s group found that the mechanical properties of their glassy gel include shape memory, self-healing, and adhesion. While other materials may demonstrate comparable toughness and stretchiness, the glassy gel offers an advantage because of its simple curing process. This work was published in a recent issue of Nature. 

In this podcast episode, MRS Bulletin’s Laura Leay interviews Coskun Kocabas from The University of Manchester in the UK about his development of a metamaterial that can tailor thermal emission. Rather than using a periodic system, which most topological materials employ, his research team borrowed a concept from laser design and created an optical cavity using a dielectric medium sandwiched between two layers that act as mirrors: a metal substrate and a top layer of platinum. The top layer serves as a thermal emitter, and the thickness of the top layer defines the topological property that regulates thermal emissivity. This work was published in a recent issue of Science. 

In this podcast episode, MRS Bulletin’s Laura Leay interviews Rasmus Neilsen from the Technical University of Denmark about his fabrication of a monolithic selenium/silicon tandem solar cell. The selenium forms the top cell of the tandem device, with silicon used as the bottom cell. Selenium-based single-junction solar cells have traditionally used fluorine-doped tin oxide. In this work indium-tin oxide was used as a transparent conductive layer that is easier to deposit and its use is more widespread. Neilsen and his research team controlled the thickness of the carrier-selective contacts in the silicon solar cell that protects the silicon layer from the processes used to deposit subsequent layers on top, thus enabling them to deposit the top cell directly onto the substrate. This work was published in a recent issue of PRX Energy. 

In this podcast episode, MRS Bulletin’s Sophia Chen interviews Mihir Pendharkar of Stanford University about characterizing electronic properties of twistronics materials. Twistronics refers to a type of electronic device consisting of two-dimensional materials layered at a relative twist angle, forming a new periodic structure known as moiré superlattices. Pendharkar and colleagues studied different configurations of graphene layered with hexagonal boron nitride. Determining the twist angle of any particular sample is extremely time-consuming. By developing a characterization technique called torsional force microscopy, Pendharkar and colleagues have reduced the time to a matter of hours. This work was published in a recent issue of Proceedings of the National Academy of Sciences. 

In this podcast episode, MRS Bulletin’s Laura Leay interviews Falon Kalutantirige from the University of Illinois Urbana-Champaign and Ying Li from the University of Wisconsin-Madison about their approach and discovery when characterizing nanovoids in polymer films. Using polyamide (PA) membranes as their subject of study, the researchers applied graph theory combined with electron tomography and molecular dynamics simulations to characterize the morphology of the nanovoids. The key to understanding permeance of the membranes lies in understanding the void space that was mapped using electron tomography. Using their mixed-method approach, the researchers were able to relate the nanoscale morphology to membrane function. Taking this beyond the study of PA membranes, the research team showed how nanovoids impact the synthesis‒morphology‒function relationships of complex nanomaterials. This work was published in a recent issue of Nature Communications. 

In this podcast episode, MRS Bulletin’s Laura Leay interviews Alexandre Dmitriev from the University of Gothenburg, Sweden about his group’s computational model of a three-dimensional metamaterial exhibiting a magnetoelectric effect—known as the Tellegen effect—when exposed to light. The building blocks of the metamaterial are comprised of disks of silicon, 150 nm in diameter, supporting a cylinder of cobalt. Silicon is chosen for its high refractive index and cobalt for its magnetic properties. These building blocks are randomly distributed in a host medium such as water or a polymer. The metamaterial has applications in areas such as improving the efficiency of solar cells, creating one-way glass, or improving lasers. It also has the potential to revolutionize how the universe is understood and could hold the key to studying dark matter. This work was published in a recent issue of Nature Communications.

In this podcast episode, MRS Bulletin’s Laura Leay interviews Antonio Dominguez-Alfaro from the University of Cambridge, UK about the development of a single-step manufacturing approach for a multimaterial 3D-printing method. The research team created two inks. One ink is a polymeric deep eutectic solvent – polyDES – made by combining and heating two salts to form a deep eutectic monomer and adding a photo-initiator to allow the ink to be cured. This ink is an ionic conductor so can capture signals from neurons inside a biological system. The other ink was based on the polymer Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which is commonly used in bioelectronics as a mixed electronic and ionic conductor. The work resolves many challenges of applying additive manufacturing in the field of bioelectronics. This work was published in a recent issue of Advanced Science. 

In this podcast episode, MRS Bulletin’s Elizabeth Wilson interviews postdoctoral researcher M. Iqbal Bakti Utama of Northwestern University about a method allowing single photon production without defect. Aryl diazonium chemistry has been used in the past to functionalize the surface of carbon nanotubes. Utama’s group found that this chemistry also works for tungsten diselenide surfaces. The group immersed tungsten diselenide monolayers into an aqueous solution of 4-nitrobenzene-diazonium tetrafluoroborate. The electrophilic molecules withdraws electrons from the monolayer, creating aryl diazonium radicals. These radicals react with each other to form nitrophenyl oligomer chains. Instead of binding covalently to the monolayer surface, the oligomers form an adlayer that is physisorbed on the tungsten diselenide surface. The spectra of photons generated when the research team irradiated the coated surface was vastly simpler than the uncoated monolayer. This work was published in Nature Communications.

In this podcast episode, MRS Bulletin’s Sophia Chen interviews Irmgard Bischofberger of the Massachusetts Institute of Technology about her investigation of how chirality emerges in nature. She uses liquid crystal molecules of disodium chromoglycate in her studies. When the molecules are dissolved in water, they form linear rods. The research group then forces the rods through a microfluidic cell, causing the rods to assemble into spiral structures without mirror symmetry. The achiral structure transformed into a chiral one. What is unique, says Bischofberger, is that the new material is composed of non-chiral building blocks. This work was published in a recent issue of Nature Communications. 

In this podcast episode, MRS Bulletin’s Laura Leay interviews Eric Pop, Xiangjin Wu, and Asir Intisar Khan from Stanford University about their work building a phase-change memory superlattice at the nanoscale. They created the superlattice by alternating layers of antimony-tellurium nanoclusters with a nanocomposite made from germanium, antimony, and tellurium (GST467). Each layer is ~2 nm thick and the superlattice consists of 15 periods of these alternating layers. The microstructural properties of GST467 and its high crystallization temperature facilitate both faster switching speed and improved stability. The device operates at low voltage and shows promise for high-density multi-level data storage. This work was published in a recent issue of Nature Communications.