GEN-ERIC News

Innovalight creates nanoparticles of silicon that it uses to make ink “and we can end up with something that looks not very different from what a solar cell looks like today, except we got there substantially faster and cheaper, and we use less material,” he said. The goal is to achieve “double digit” efficiency, higher than current levels for other thin-film-based solar cells, although Burke wouldn’t reveal a specific number. The industry standard is 14 or 15 percent, although some companies talk about reaching 20 percent efficiency. Efficiency measures the percentage of absorbed light converted to electricity.

A single solar cell produces a relatively low output – it’s a case of strength in numbers. Tiny strips of metal are used to link cells together. If the laser soldering temperature is too high, the solder joint may fracture. A new system provides automatic temperature regulation. Teamwork is what matters – even in the case of solar cells: To obtain sufficient power to operate a pocket calculator, parking ticket dispenser or photovoltaic module, sunlight has to be captured simultaneously by an array of cells. They are connected in series using tiny strips of metal known as stringers. Each stringer has to be positioned in precisely the right spot, then its solder coating is melted using a hot electrode. Researchers at the Fraunhofer Institute for Laser Technology have developed a non-contact soldering system in which the temperature is constantly monitored.

“Integrating a high-quality film of silicon nanoparticles 1 nanometer in size directly onto silicon solar cells improves power performance by 60 percent in the ultraviolet range of the spectrum,” said Munir Nayfeh, a physicist at the University of Illinois and corresponding author of a paper accepted for publication in Applied Physics Letters. A 10 percent improvement in the visible range of the spectrum can be achieved by using nanoparticles 2.85 nanometers in size, said Nayfeh, who also is a researcher at the university’s Beckman Institute. In conventional solar cells, ultraviolet light is either filtered out or absorbed by the silicon and converted into potentially damaging heat, not electricity. In previous work, however, Nayfeh showed that ultraviolet light could efficiently couple to correctly sized nanoparticles and produce electricity. That work was reported in the August 2004 issue of the journal Photonics Technology Letters.

Steve Arms started by designing sensors that could be arthroscopically implanted to measure strain on knee ligaments. These days, Arms and his company, MicroStrain Inc., are experimenting with wireless sensing technology that could play a bigger role in assessing the condition of bridges after one in Minneapolis collapsed two weeks ago, killing at least nine people. The wireless, solar-powered sensor system can provide data on strain, seismic activity and vibrations on bridges, eliminating the need to manually replace batteries once the sensors are installed in hard-to-access places. Already in place on the Corinth Canal Bridge in Greece and an Interstate 95 bridge in New London, Conn., the sensors harvest energy from the sun using 6-by-9-inch photovoltaic panels. The panels are linked to rechargeable batteries and power microelectronic modules that record data from inside watertight enclosures. The data is transmitted to computers via wireless connections.