Reported widely late last year as a “Junkyard Wars” contraption, University of Toronto researcher Illan Kramer’s spray rig for coating just about anything with a thin film of colloidal quantum dots (QCDs) offers the potential for making Kramer’s hopes come true. “My dream is that one day you’ll have two technicians with Ghostbusters backpacks come to your house and spray your roof.” Kramer is a post-doctoral fellow with The Edward S. Rogers Sr. Department of Electrical & Computer Engineering at the University of Toronto and IBM Canada’s Research and Development Centre. His spray equipment, composed of a “spray nozzle used in steel mills to cool steel with a fine mist of water, and a few regular air brushes from an art store,” manages to spread colloidal quantum dots with the precision usually found in atomic layer deposition managed in laboratory or carefully-controlled manufacturing conditions. He admits to the unaesthetic look of the setup, but notes that the $1,000 sprayLD system …
Graphene Works and Plays Well With Other Materials
Graphene is a highly promising material, one atom thick, strong enough to support an elephant standing on a pencil (only theoretically so far, with no actual demonstration having taken place), and electrically conductive. All these properties bode well for its use in batteries, solar cells, and even energy-storing structural members. One concern, however, has been in how graphene would interact with other materials in a practical setting. After all, so far most experiments with graphene have taken place at the atomic level, not a feasible working arrangement for the ham-handed and those without scanning electron microscopes in their garage workshops. Dr. Marc Gluba and Professor Dr. Norbert Nickel of the Helmholz Zentrum Berlin have, doubtless with some pretty intense tools available at their Institute for Silicon Photovoltaics, managed to coat a graphene film with a thin silicon film. According to the Institute, “They grew graphene on a thin copper sheet, next transferred it to a glass substrate, and finally coated …
Lithium Gets a Good Wrap
Shadi Dayeh, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering, has been designing new electrode architectures that could solve one of lithium batteries’ biggest problems. When lithium diffuses across the surface of a lithium-ion battery electrode, it causes the electrode to expand and contract depending on its charging or discharging. This eventually leads to cracking and ultimate disintegration of the anode or cathode – weakening and finally disabling the battery. Dayeh, working with colleagues at the University and Sandia and Los Alamos National Laboratories, came up with nanowires that, “Block diffusion of lithium (Li) across their silicon surface and promote layer-by-layer axial lithiation of the nanowire’s germanium core.” Seeing possibilities beyond his current research, Dayeh says the work could lead to, “An effective way to tailor volume expansion of lithium ion battery electrodes which could potentially minimize their cracking, improve their durability, and perhaps influence how one could think about …
5X Batteries? How About 70,000X Solar Cells?
Matt Shipman of North Carolina State University News Services reports on a connector that could allow stacking solar cells without losing voltage. This stacking could allow cells to operate at solar concentrations of “70,000 suns worth of energy without losing much voltage as ‘wasted energy’ or heat.” This could have tremendous implications improving the overall efficiency of solar energy devices and reducing the cost of solar energy production. Stacked solar cells live up to their name, simply being several cells stacked on one another, with their layering leading to up to 45-percent efficiency in converting solar energy into electricity. So far, the big drawback has been the junctions between cells, which tend to waste the energy from the connected cells as heat. Dr. Salah Bedair, a professor of electrical engineering at NC State and senior author of a paper describing the work says, “We have discovered that by inserting a very thin film of gallium arsenide into the connecting junction of …
Solar Cells – All That Glitters Need Not Be Gold
The search for less expensive solar cells drives many lines of research these days, with trends toward smaller collectors and less expensive materials leading the way. Many solar cells use gold and other pricey metals to provide junctions within the cell structure. Gold closed Friday at $1,204.00 per troy ounce on the London Metal Exchange, and nickel at $10.01 per pound. That would make gold worth $17,558 per avoirdupois pound (14.583 troy ounces per pound), or 1,754 times more expensive than nickel. According to Gizmag, University of Toronto investigators found that substituting nickel for the previously used gold as collection contacts in their colloidal quantum dot solar cells provided equal performance, at a 40 to 80-percent drop in solar cell prices. Following that math, current pricing of solar cells such as Ascent’s thin film units at $6.00 per Watt could drop to $2.40 to $1.20 per Watt; near the $1.00 per Watt goal many cell makers have long sought. …