{"id":7932,"date":"2013-06-27T09:54:23","date_gmt":"2013-06-27T16:54:23","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=7932"},"modified":"2013-06-27T09:54:23","modified_gmt":"2013-06-27T16:54:23","slug":"thinner-than-kleenex-as-powerful-as-the-sun","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/thinner-than-kleenex-as-powerful-as-the-sun\/","title":{"rendered":"Thinner than Kleenex\u00ae, as Powerful as the Sun"},"content":{"rendered":"

David L. Chandler of the Massachusetts Institute of Technology (MIT) News Office<\/a> reports that an MIT research team headed by Jeffrey Grossman has found a way to make sheets that push \u201ctowards the ultimate power conversion from a material\u201d for solar power.\u00a0 His team has managed to fabricate molecule-thick photovoltaic sheets which could pack hundreds of times more power per weight than conventional solar cells.<\/p>\n

Senior author of a new paper on the team\u2019s study in Nano Letters<\/em><\/a>, Grossman found that despite the interest in two-dimensional materials such as graphene \u2013 only an atom thick \u2013 few have studied their potential for solar applications.\u00a0 Grossman says, \u201cThey\u2019re not only OK, but it\u2019s amazing how well they do.\u201d<\/p>\n

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The MIT team found that an effective solar cell could be made from a stack of two one-molecule-thick materials: Graphene (a one-atom-thick sheet of carbon atoms, shown at bottom in blue) and molybdenum disulfide (above, with molybdenum atoms shown in red and sulfur in yellow). The two sheets together are thousands of times thinner than conventional silicon solar cells.\u00a0Graphic: Jeffrey Grossman and Marco Bernardi<\/p><\/div>\n

Stacking sheets of graphene and materials such as molybdenum disulfide would make solar cells with one to two percent efficiency in converting sunlight to electricity.\u00a0 That seems disappointingly low compared to the 15 to 20 percent efficiency of commercially available silicon solar cells.<\/p>\n

One nanometer thick, this material is thousands of times thinner and lighter than tissue paper, though, and stacking multiple layers of the tissue-like films would create significant increases in energy collection efficiency.\u00a0 Postdoctoral candidate Marco Bernardi was lead author on the team\u2019s paper and thinks, \u201cStacking a few layers could allow for higher efficiency, one that competes with other well-established solar cell technologies.\u201d\u00a0 Maurizia Palummo, a senior researcher at the University of Rome visiting MIT through the MISTI Italy program, was also a co-author.<\/p>\n

Bernardi says that pound for pound, the thin cells could produce up to 1,000 times more power than conventional cells.\u00a0 Their billionth of a meter thickness is about \u201c20 to 50 times thinner than the thinnest solar cell that can be made today.\u00a0 You couldn\u2019t make a solar cell any thinner,\u201d according to Grossman.<\/p>\n

Because so little material is needed to make such thin stuff, and the costs of materials are far lower than those for silicon cells, these should be low-budget offerings compared to today\u2019s solar panels.\u00a0 Because the material is relatively stable, it can be used in open-air applications with no need for glass covers such as silicon panels require.<\/p>\n

Applications in aircraft use are immediately apparent, although thin sheets that could be applied to other structures such as houses would have many benefits.\u00a0 MIT says, \u201cAbout half the cost of today\u2019s panels is in support structures, installation, wiring and control systems, expenses that could be reduced through the use of lighter structures.\u201d<\/p>\n

Grossman reflected on the theoretical nature of the work so far, leaving many avenues open to explore.\u00a0 \u201cThere\u2019s a whole zoo of these materials that can be explored. My hope is that this work sets the stage for people to think about these materials in a new way.\u201d\u00a0 Molybdenum disulfide and molybdenum diselenide are the two-dimensional materials studied so far, but the \u201czoo\u201d is open.\u00a0 The team can only speculate at this point on the many other materials available, and the innumerable combinations that could increase efficiency.<\/p>\n

As the team moves beyond computer modeling to actually producing working samples of these materials and discovering ways in which they could be produced at a commodity level, the potential for transforming energy collection and applying these breakthroughs to transportation will also transform what our future aircraft will look like and how they will perform.<\/p>\n

This work was supported by the MIT Energy Initiative.<\/p>\n

(Self-serving Advertisement Warning: Your editor has an article in the July, 2013 issue of Kitplanes magazine called, \u201cThe Grand Unified Airplane,\u201d which details how materials science could lead to aircraft that ultimately \u00a0take their power from the \u201cvery act of flight itself.\u201d\u00a0 MIT\u2019s work certainly points to one way this could happen<\/em>.)<\/p>\n

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