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Highlights

Accelerated searches, made possible by machine learning techniques, are of growing interest in materials discovery. A suitable case involves the solution processing of components that ultimately form thin films of solar cell materials known as Hybrid Organic-Inorganic Perovskites (HOIPs). The number of molecular species that combine in solution to form these films constitutes an overwhelmingly large “compositional" space (at times, exceeding 500,000 possible combinations). Selecting a HOIP with desirable characteristics involves choosing different cations, halides, and solvent blends from a diverse palette of options. An unguided search by experimental investigations or molecular simulations is prohibitively expensive. In this work, we propose a novel Bayesian optimization method that overcomes challenges where data is scarce, and in which the search space is given by binary variables indicating whether a constituent is present or not. We demonstrate that the proposed approach identifies HOIPs with the targeted maximum intermolecular binding energy between HOIP salt and solvent at considerably lower cost than previous state-of-the-art Bayesian optimization methodology and at a fraction of the time (less than 10 per cent) needed to complete an exhaustive search. We find an optimal composition within 15 iterations (plus or minus 10) in a HOIP compositional space containing 72 combinations, and within 29 iterations (plus or minus 11) when considering mixed halides (240 combinations). Exhaustive quantum mechanical simulations of all possible combinations were used to validate the optimal prediction from a Bayesian optimization approach. These proofs of concept demonstrate the undeniable promise of the novel Bayesian optimization methodology, presented here, to the field of materials discovery. H. Herbol et al., Nature Comp. Materials, under review (2018)
Accelerated searches, made possible by machine learning techniques, are of growing interest in materials discovery. A suitable case involves the solution processing of components that ultimately form thin films of solar cell materials known as Hybrid Organic-Inorganic Perovskites (HOIPs). The number of molecular species that combine in solution to form these films constitutes an overwhelmingly large “compositional" space (at times, exceeding 500,000 possible combinations). Selecting a HOIP with desirable characteristics involves choosing different cations, halides, and solvent blends from a diverse palette of options. An unguided search by experimental investigations or molecular simulations is prohibitively expensive. In this work, we propose a novel Bayesian optimization method that overcomes challenges where data is scarce, and in which the search space is given by binary variables indicating whether a constituent is present or not. We demonstrate that the proposed approach identifies HOIPs with the targeted maximum intermolecular binding energy between HOIP salt and solvent at considerably lower cost than previous state-of-the-art Bayesian optimization methodology and at a fraction of the time (less than 10 per cent) needed to complete an exhaustive search. We find an optimal composition within 15 iterations (plus or minus 10) in a HOIP compositional space containing 72 combinations, and within 29 iterations (plus or minus 11) when considering mixed halides (240 combinations). Exhaustive quantum mechanical simulations of all possible combinations were used to validate the optimal prediction from a Bayesian optimization approach. These proofs of concept demonstrate the undeniable promise of the novel Bayesian optimization methodology, presented here, to the field of materials discovery. H. Herbol et al., Nature Comp. Materials, under review (2018)
Jun 5, 2018
Cornell Center for Materials Research (2017)

Using Math to Search for a 'Needle in a Haystack' to Make Better Solar Cells
CCMR researchers have used mathematical methods, typically used in business forecasting, to suggest which combination of components will make the best solar cell materials in a “perovskite” arrangement. These materials are made in solution, essentially in a beaker, at room temperature. This makes them far more energy-conservative than traditional silicon solar cells. But researchers are spoiled for choice in terms of components that could be put into the “soup;” too many to make in the lab.
May 30, 2018
CRISP: Center for Research on Interface Structures and Phenomena (2011)

Enhancement of the Quality Factor of Metallic Glass Resonators via Cyclic Shear Training

O’Hern and Schroers, Yale University  
Metallic glass resonators can possess larger quality factors (i.e., slower rates of energy dissipation) than typical polycrystalline metals, since metallic glasses are spatially homogeneous without dislocations and other topological defects. Using numerical simulations, we studied the energy dissipation mechanisms and  measured the quality factor Q in model metallic glass cantilevers (panel (a)). We bend the cantilever to a given strain ε, release it, and measure Q from the Fourier transform of the cantilever displacement as a function of time.
Teachers gained first hand experience on manufacturing equipment at Platt Technical HS, learning what skills their students need.
Teachers gained first hand experience on manufacturing equipment at Platt Technical HS, learning what skills their students need.
May 30, 2018
CRISP: Center for Research on Interface Structures and Phenomena (2011)

Materials & Manufacturing Summer Teachers’ Institute (MMSTI)

Center for Research on Interface Structures and Phenomena, Yale University & Southern Connecticut State University  
The Materials and Manufacturing Summer Teachers’ Institute is a school-to-career initiative that targets STEM skills instruction for grades 7-12 in the New Haven and Bridgeport Public Schools. Three-day workshop designed to:
Simulation snapshots of meso-phases formed by H(CHOH)x(CH2)yH oligomers (polar in red and nonpolar in cyan) including Lamellae, Perforated Lamellae, Cylinders, and Disordered Micelles. The numbers indicate the domain periods.
Simulation snapshots of meso-phases formed by H(CHOH)x(CH2)yH oligomers (polar in red and nonpolar in cyan) including Lamellae, Perforated Lamellae, Cylinders, and Disordered Micelles. The numbers indicate the domain periods.
May 25, 2018
UMN Materials Research Science and Engineering Center (2014)

Computational Design of High-χ Block Oligomers for Accessing 1-nm Features

Marc Hillmyer, Timothy Lodge, Ilja Siepmann University of Minnesota
The ability to precisely predict how molecular structure influences the microstructure of polymeric materials is the key towards the custom tailoring of desirable materials properties. Molecular dynamics simulations with atomistic level models were performed to design “high-χ” block oligomers that can self-assemble into 1-5 nm domains for next generation microelectronics applications. Simulations show that the microstructures formed by these oligomers can be tuned by varying the molecular weight and the chain architecture.
Precise control over defects in materials is often a highly effective means to control properties and function. In oxide materials, which are the focus of enormous current attention for many existing and proposed applications, defects known as oxygen vacancies often play the key role. These vacancies, simply missing oxygen atoms in the structure, can have a significant impact on properties.
Precise control over defects in materials is often a highly effective means to control properties and function. In oxide materials, which are the focus of enormous current attention for many existing and proposed applications, defects known as oxygen vacancies often play the key role. These vacancies, simply missing oxygen atoms in the structure, can have a significant impact on properties.
May 24, 2018
UMN Materials Research Science and Engineering Center (2014)

Glass-like Thermal Conductivity in Epitaxial Oxygen-Vacancy-Ordered Oxide Films

Xiaojia Wang, Chris Leighton University of Minnesota
Precise control over defects in materials is often a highly effective means to control properties and function. In oxide materials, which are the focus of enormous current attention for many existing and proposed applications, defects known as oxygen vacancies often play the key role. These vacancies, simply missing oxygen atoms in the structure, can have a significant impact on properties.
May 22, 2018
Wisconsin Materials Research Science and Engineering Center

IRG1: Increased Stability of CuZrAl Metallic Glasses Prepared by Physical Vapor Deposition

George B. Bokas and Izabela Szlufarska, University of Wisconsin-Madison MRSEC  
One of the main drawbacks of metallic glasses is their low thermodynamic stability, which limits their formability and service life.  Recently, experiments by members of the Wisconsin MRSEC showed that organic glasses with high thermodynamic stability can be synthesized via physical vapor deposition (PVD) onto a substrate at a controlled temperature.  Now, this team of researchers has used molecular dynamics simulations to predict that the same PVD methods can enhance the stability of metallic glasses. 
MRSEC members generate ideas for digital games (top left). Two games, Atom Touch (top right) and Crystal Cave (bottom left), have been played over 33,000 times since they were released. Students test the games (bottom right) to help improve them.
MRSEC members generate ideas for digital games (top left). Two games, Atom Touch (top right) and Crystal Cave (bottom left), have been played over 33,000 times since they were released. Students test the games (bottom right) to help improve them.
May 22, 2018
Wisconsin Materials Research Science and Engineering Center

Wisconsin MRSEC Researchers and Teachers Collaborate to Create Digital Educational Games

Anne Lynn Gillian-Daniel, University of Wisconsin-Madison MRSEC  
The Wisconsin MRSEC has developed research-inspired educational digital games that are each being played over 1900 times/week. Atom Touch teaches students about atom behavior, bonding, and forces. Crystal Cave lets students explore how molecules form repeating patterns to grow into large crystals.  During development, local K-12 teachers provided input on how to make the games more engaging for student learning.
(Top) World Science Festival booth led by high school and undergraduate students. (bottom) Workshop session pre-WSF for teaching modules.
(Top) World Science Festival booth led by high school and undergraduate students. (bottom) Workshop session pre-WSF for teaching modules.
May 18, 2018
NYU Materials Research Science and Engineering Center (2014)

World Science Festival: Crystals, Colloids and Fun!

NYU-MRSEC investigators along with research scientist from the BioBus/BioBase organization mentored nine high school students as part of a two month peer-mentorship program.  The idea, to train high school students in optics, CAD/3D printing and basic of microscopy including applications in materials science (crystals and colloids).
May 18, 2018
NYU Materials Research Science and Engineering Center (2014)

Phases of Matter – Adult Coloring Book
MRSEC investigators team-up to create an adult coloring book. The coloring book, “Phases of Matter,” designed to help the general pubic understand physics and phase behavior.
May 18, 2018
NYU Materials Research Science and Engineering Center (2014)

Freezing on a Sphere

Andrew D. Hollingsworth & Paul M. Chaikin, New York University
A crystal is defined by the regular and periodic ordering of the atoms, molecules, or particles that compose them.  If bent or strained, this order and regularity is disturbed, and defects appear that relieve some of the applied stress.

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