Less can be more: Semiconductor nanowires fo…

Less can be more: Semiconductor nanowires for flexible photovoltaics

Capturing and manipulating light at nanoscale is a key factor to build high efficiency solar cells. Researchers in the 3-D Photovoltaics group have recently presented a promising new design. Their simulations show that vertically stacked nanowires on top of ultrathin silicon films reduces the total amount of material needed by 90 percent while increasing the efficiency of the solar cell. These promising simulation results are an important step toward next-generation solar cells. The results have been published on May 23rd in Optics Express.

A strategy to reduce cost and rigidity of photovoltaics is to combine ultrathin silicon photovoltaic films with semiconductor nanowire solar cells. The mechanical flexibility and resilience of micrometer thin cells make them well suited to apply on curved surfaces.

The idea is to optically couple the two materials stacked on top of each other as a tandem cell: a gallium arsenide (GaAs) nanowire array on top of an ultrathin silicon (2um-thick) film. GaAs vertical nanowires are well-known semiconductor components in photovoltaic applications.

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Researchers create soft, flexible materials …

Researchers create soft, flexible materials with enhanced properties

A team of polymer chemists and engineers from Carnegie Mellon University have developed a new methodology that can be used to create a class of stretchable polymer composites with enhanced electrical and thermal properties. These materials are promising candidates for use in soft robotics, self-healing electronics and medical devices. The results are published in the May 20 issue of Nature Nanotechnology.

In the study, the researchers combined their expertise in foundational science and engineering to devise a method that uniformly incorporates eutectic gallium indium (EGaIn), a metal alloy that is liquid at ambient temperatures, into an elastomer. This created a new material—a highly stretchable, soft, multi-functional composite that has a high level of thermal stability and electrical conductivity.

Carmel Majidi, a professor of Mechanical Engineering at Carnegie Mellon and director of the Soft Machines Lab, has conducted extensive research into developing new, soft materials that can be used for biomedical and other applications. As part of this research, he developed rubber composites seeded with nanoscopic droplets of liquid metal. The materials seemed to be promising, but the mechanical mixing technique he used to combine the components yielded materials with inconsistent compositions, and as a result, inconsistent properties.

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cenchempics: Liquid metal ferrofluid Ferroflu…


Liquid metal ferrofluid

Ferrofluids are liquids, often oils, in which tiny particles of a magnetic material such as iron are suspended, allowing scientists to stretch and shape them with magnetic fields. Now, researchers have made one (shown being manipulated with magnets) where the fluid is a liquid metal alloy of gallium, indium, and tin at a ratio of 67:12:13. Because the ferrofluid conducts electricity readily, the team predicts it might one day be used in new types of remote and 3-D electrical switches, as well as in soft robotics. —Craig Bettenhausen

Credit: ACS Appl. Mater. Interfaces 2019, DOI: 10.1021/acsami.8b22699

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New technique could pave the way for simple …

New technique could pave the way for simple color tuning of LED bulbs

Volkmar Dierolf and an international team demonstrate the possibility of tuning the color of a GaN LED by changing the time sequence at which the operation current is provided to the device.

A new technique―the result of an international collaboration of scientists from Lehigh University, West Chester University, Osaka University and the University of Amsterdam―could pave the way for monolithic integration for simple color tuning of a light bulb, according to Volkmar Dierolf, Distinguished Professor and Chair of Lehigh’s Department of Physics, who worked on the project.

“This work could make it possible to tune between bright white and more comfortable warmer colors in commercial LEDs,” says Dierolf.

The team demonstrated the possibility of color tuning Gallium Nitride (GaN)-based GaN LEDs simply by changing the time sequence at which the operation current is provided to the device. Light-emitting diodes or LEDs are semiconductor devices that emit light when an electric current is passed through it. Notably, the technique is compatible with current LEDs that are at the core of commercial solid state LED lighting.

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Oregon scientists drill into white graphene to…

Oregon scientists drill into white graphene to create artificial atoms: Patterned on a microchip and working in ambient conditions, the atoms could lead to rapid advancements in new quantum-based technology

By drilling holes into a thin two-dimensional sheet of hexagonal boron nitride with a gallium-focused ion beam, University of Oregon scientists have created artificial atoms that generate single photons.


The artificial atoms – which work in air and at room temperature – may be a big step in efforts to develop all-optical quantum computing, said UO physicist Benjamín J. Alemán, principal investigator of a study published in the journal Nano Letters.

“Our work provides a source of single photons that could act as carriers of quantum information or as qubits. We’ve patterned these sources, creating as many as we want, where we want,” said Alemán, a member of the UO’s Material Science Institute and Center for Optical, Molecular, and Quantum Science. “We’d like to pattern these single photon emitters into circuits or networks on a microchip so they can talk to each other, or to other existing qubits, like solid-state spins or superconducting circuit qubits.”

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