A new manufacturing method that incorporates laser technology may result in thin film solar panels that are less expensive and more efficient than anything presently on the market. Currently, a stylus is used to mechanically etch microchannels into such panels, which electrically connect the individual solar cells and allow them to form an array. Researchers from Indiana's Purdue University, however, are developing a technique in which an ultrafast pulsing laser is used to do the etching. Not only will it hopefully be quicker and cheaper than mechanical "scribing," but it should also produce cleaner, sharper microchannels that offer superior performance.
"The mechanical scribing methods in commercial use do not create high-quality, well-defined channels," said Yung Shin, director of Purdue's Center for Laser-Based Manufacturing. "Although laser scribing has been studied extensively, until now we haven't been able to precisely control lasers to accurately create the microchannels to the exacting specifications required."
Shin's team has addressed the lack of control by using an ultrashort-pulse laser, the individual pulses of which last for only picoseconds, or quadrillionths of a second. The etching process utilizes what is known as "cold ablation," in that the pulse times are so short that the thin film doesn't suffer any heat damage.
"It creates very clean microchannels on the surface of each layer," Shin said. "You can do this at very high speed, meters per second, which is not possible with a mechanical scribe. This is very tricky because the laser must be precisely controlled so that it penetrates only one layer of the thin film at a time, and the layers are extremely thin. You can do that with this kind of laser because you have a very precise control of the depth, to about 10 to 20 nanometers."
The research project will continue for a three year period, by the end of which which the scientists hope to have established the scientific basis for their laser-ablation technique.
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