- Education & Outreach
- Roll-to-Roll Fabrication and Processing Facility
- Nanoimprint Lithography & Hybrid Coating R2R Coaters
- Conte Nanotechnology Cleanroom Lab
- Nuclear Magnetic Resonance Facility
- UMass-Amherst Mass Spectrometry Center
- UMass Amherst Electron Microscopy Center
- Hysitron Triboindenter
- Nanonex Nanoimprinter
Scientists have created hybrid perovskite-graphene solar cells that show good stability upon exposure to sunlight, while still maintaining efficiency over 18% - the highest reported efficiency of...
<?xml version="1.0" encoding="UTF-8"?> Fractals and biomimetics just helped to surpass the performance of today’s transparent electrode materials Image: M. Giersig/HZB If you take a close look at a leaf from a tree and you’ll notice the veins that run through it. The structure these veins take are what’s called a quasi-fractal hierarchical networks. Fractals are geometric shapes in which each part has the same statistical character of the whole. Fractal science is used to model everything from snowflakes and the veins of leaves to crystal growth. Now an international team of researchers led by Helmholtz-Zentrum Berlin have mimicked leaves’ quasi-fractal structure and used it to create a network of nanowires for solar cells and touch screen displays. Indium tin oxide (ITO) has been the go-to material for transparent conductors in displays and solar cells. While the costs associated with ITO have been one of the main knocks against it, it’s been difficult for the various nanomaterials proposed as alternatives to replace it. Nanomaterials—including silver nanowires, carbon nanotubes and graphene—have not only been handicapped by their own relative high costs, but their performance has been somewhat lacking as well. With this new method of distribution, nanowires are able to surpass the performance of traditional ITO layers. The reason for this becomes a little clearer when you go back and look at the leaf. The distribution of veins in the leaf is determined in part by the amount of shade and sunlight the leaf receives. With ITO, the material is spread out in one continuous, uniform film. However, the way the sunlight strikes a solar cell or the way a finger presses on a touch-screen display are not uniform. This reduces the ITO layer’s efficiency. In research described in the journal Nature Communications , the international research team used a quasi-fractal hierarchical network to optimize the distribution of the nanowires on a solar cell according to three conditions: provide maximum surface coverage, achieve a uniform current density, and have a minimal overall resistance. “On the basis of our studies, we were able to develop an economical transparent metal electrode," Michael Giersig, a professor at Helmholtz-Zentrum Berlin and who led the research, said in a press release. “We obtain this by integrating two silver networks. One silver network is applied with a broad mesh spacing between the micron-diameter main conductors that serve as the ‘highway’ for electrons transporting electrical current over macroscopic distances.” Next to this broad highway for the electrons, the researchers added randomly distributed nanowire networks that serve as local conductors to cover the surface between the large mesh elements. “These smaller networks act as regional roadways beside the highways to randomize the directions and strengths of the local currents, and also create refraction effects to improve transparency,” according to Giersig. Solar cells with the leaf-vein network had an efficiency of 5.91 percent in experiments. Those with a standard ITO had 5.37 percent.
A transparent flexible thin-film triboelectric nanogenerator for scalable electricity generationGuang Zhu; Xiao Yan Wei; Zhong Lin WangInternational Journal of Nanomanufacturing, Vol. 12, No. 3/4 (2016) pp. 396 - 403We report a flexible thin-film-based triboelectric nanogenerator (TF-TENG) that has a one-component laminated structure as thin as 100 µm. The electricity-generating process of the TF-TENG takes advantage of the interaction between the TF-TENG and an external object that carries triboelectric charge on the surface. The motion of the object creates electric potential difference between two electrodes on the TF-TENG, which then produces electron flow in the external circuit. When triggered by foot stomping, a TF-TENG (20 cm by 20 cm) spread on the floor could generate an open-circuit voltage of 700 V, a short-circuit current of 3 mA, and an instantaneous power of 168 mW that corresponds to a power density of 4.2 W/m<SUP align="right">2</SUP>. The generated electricity could simultaneously power 1,000 LEDs. The TF-TENG can be tailored to any desired size and shape that are suitable in a variety of circumstances as long as contacts with external objects take place. When the TF-TENG is scaled up in area and used in places that have large flows of people such as subway stations and shopping malls, the produced electric energy in total may become considerable.
Ambitious, complex research that leads to breakthrough discoveries requires large-scale, long-term investments. Today, the National Science Foundation (NSF) announces $94 million in funding to support four new Science and Technology Centers (STCs), partnerships that lay the foundations for advances in fields ranging from cell biology and mechanobiology to particle physics and materials science. Each awardee will receive up to $24 million over a five-year period, with the possibility ... More at http://www.nsf.gov/news/news_summ.jsp?cntn_id=189782&WT.mc_id=USNSF_51&WT.mc_ev=click This is an NSF News item.
Deep insights from surface reactions: Researchers use Stampede supercomputer to study new chemical sensing methods, desalination and bacterial energy production
Things that happen on the surface are often given short shrift compared to what goes on inside. But when it comes to chemical reactions, what occurs on the surface can mean the difference between a wo...
Researchers from Brown University have demonstrated an unusual method of putting the brakes on superconductivity, the ability of a material to conduct an electrical current with zero resistance.
Research from the University of Surrey reveals scientists are able to improve the efficiency of solar cells more than threefold The solar cells are a flexible, lightweight and environmentally-frien...
New technology of ultrahigh density optical storage researched at Kazan University: The ever-growing demand for storage devices stimulates scientists to find new ways of improving the performance of existing technologies
According to current estimates, dozens of zettabytes of information will need to be placed somewhere by 2020. New physical principles must be found, the ones that facilitate the use of single atoms or...
The discovery of photoemission, the emission of electrons from a material caused by light striking it, was an important element in the history of physics for the development of quantum mechanics. Scie...
Physics, photosynthesis and solar cells: Researchers combine quantum physics and photosynthesis to make discovery that could lead to highly efficient, green solar cells
A University of California, Riverside assistant professor has combined photosynthesis and physics to make a key discovery that could help make solar cells more efficient. The findings were recently pu...
New method for analyzing crystal structure: Exotic materials called photonic crystals reveal their internal characteristics with new method
A new technique developed by MIT researchers reveals the inner details of photonic crystals, synthetic materials whose exotic optical properties are the subject of widespread research.
New technique could be used to monitor how molecular transport through neurons is modified in diseases like autism and Alzheimer’s.
New technique could test fundamental principles of quantum mechanics.
Lithium-sulfur batteries (Li-S) can hold as much as five times the energy per unit mass that lithium-ion (Li-ion) batteries can. However, Li-S batteries suffer from the propensity for polysulfides to...