Published on February 17th, 2010 | by Tina Casey1
Innovalight's Silicon Ink "Tattoo" Will Lower the Cost of Solar Cells
Innovalight of Sunnyvale, California has just won a key patent for a new process that will significantly lower the cost of manufacturing silicon solar cells. Working with the National Renewable Energy Laboratory (NREL), the company has come up with a way to apply silicon ink to silicon wafers without using the expensive vacuum-based process typically in use today.
Innovalight’s process is based on an inkjet type technology for manufacturing solar cells. Compared to conventional vacuum processes, the inkjet method is significantly less expensive, and far more energy efficient. It also allows for a higher rate of production than conventional vacuum based methods.
Silicon Ink Solar Cells, Innovalight and NREL
Innovalight’s new method is based on “atmospheric processing” that eliminates the need for conventional vacuum systems. NREL has been devoting significant resources to developing technologies to bring the method into commercial use and lower the cost solar cells. A key component is the Atmospheric Processing platform, which includes a robotic 3-D inkjet system. Atmosphere within the platform can be precision controlled and monitored, to enable researchers to develop and refine the process.
Record Breaking Solar Cell Efficiency
Efficiency records for solar cells are falling so fast it’s hard to sort them all out, especially with so many new materials and technologies pouring into the market. Let’s just say that NREL and Germany’s Fraunhofer Institute for Solar Energy Systems have both certified that Innovalight’s new silicon ink processed solar cells have a conversion efficiency of 18%, which is apparently a record for that sort of technology. With several interlocking materials and processes, the company is aiming for an efficiency of 20%.
Silicon Solar Cells and the Quantum Dot Connection
Innovalight and NREL have also collaborated on research into the energy conversion potential of quantum dots (nanocrystals, aka qdots) that could lead to further improvements in silicon solar cell efficiency. The effect, called multiple exciton generation (MEG) was thought to occur only in qdots of semiconductor materials that are not used in solar cell manufacturing – and which contain toxic metals such as lead. The new research shows that MEG also occurs in silicon , which is nontoxic. This opens the door to greater efficiency, without the need to introduce more toxic materials into the environment, by capturing more of the energy from silicon solar cells that is currently lost as heat.
Solar Cell Tattoos and Solar Graffiti, Too
Ink-based solar is coming into its own, which opens up the possibility of applying solar cell “paint” directly onto buildings – or even onto people. A low cost spray-on version of solar cell technology is not far behind: scientists at the University of Texas at Austin and at Australian National University are among the teams developing a low cost, spray-on ink that could be used on rolls of plastic or stainless steel, and New Energy Technologies has even developed a transparent solar cell spray that could be applied to windows.