Energy Focus
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Nature Materials DOI: 10.1038/nmat3013
In what may be a route to the use of thermal solar energy on a small (less than industrial) scale, researchers at MIT, GMZ Energy, Boston College, and the Masdar Institute of Science and Technology in Abu Dhabi, United Arab Emirates, have reported the development of a flat-panel solar thermal to electric power conversion technology. The solar thermoelectric generator (STEG) consists of a wavelength-selective solar absorber flat panel, a pair of p- and n-type nanostructured Bi2Te3 thermoelectric elements, and two bottom electrodes that serve as heat spreaders, all enclosed in an evacuated glass chamber. This configuration enables thermal concentration sufficient to generate the necessary temperature differential of approximately 200°C across the thermoelectric device to achieve acceptable efficiencies. The researchers report an efficiency of 4.6% under AM 1.5 conditions, which they say is seven to eight times higher than the best previously reported value for a flat-panel STEG.
Scientists report flexible solar cells with record efficiency Nature Materials DOI: 10.1038/nmat3122
Scientists at Empa, the Swiss Federal Laboratories for Materials Science and Technology, have reported flexible solar cells with a world record 18.7% efficiency. The group, led by Ayodhya N. Tiwari, overcame the Flexible CIGS solar cells developed at Empa. low temperature deposition challenge posed by polymer substrates with low melting points, which in the past has limited the efficiencies of flexible solar cells. The quaternary copper indium gallium (di)selenide (CIGS) semiconductor system that absorbs light and converts it into electricity tends to suffer from composition grading when deposited at lower temperatures compatible with polymer films, because of inadequate interdiffusion of intermediate phases and preferential diffusion of gallium (Ga) toward the electrical back contact. By controlling the Ga and In evaporation flux during different stages of the evaporation process, the researchers were able to improve the composition profile to enable efficient charge-carrier collection and reduce interface recombination, resulting in the high efficiency reported.
When it comes to storing hydrogen for use in fuel cells or other devices envisioned for the “hydrogen economy,” it is not just the amount of hydrogen that a material can store, but also how Particles of pure magnesium (left) can only collect a limited amount of hydrogen on their outer surfaces, fast it can store and and the process is slow. But when the magnesium is doped with iron (right), far more hydrogen is release it that matters. delivered through the iron layers, which also results A research team at the in much faster charging. Credit: NIST National Institute of Standards and Technology (NIST) led by Leo Bendersky has recently reported a thin-film architecture involving veins of iron running through fine-grained magnesium that meets both hydrogen capacity and charge/discharge requirements. Taking advantage of the immiscibility of Mg wi
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