Photovoltaics based on the CIGS (copper indium gallium diselenide) or CIS material system have been hailed for their potential for a decade, but it's only recently that volume commercialization has begun. In 2009, 156 megawatts of CIGS PV shipped, mostly from Showa Shell (now Solar Frontier), Global Solar, and Honda, according to GTM analyst Shyam Mehta.
Big CIGS solar production is going to happen soon. It might be Solyndra, MiaSolé, Nanosolar, AQT, Global Solar, Wurth Solar, Johanna Solar or any of the many other CIGS aspirants.
It might even be First Solar that makes CIGS work in a big way. First Solar President Bruce Sohn was quoted by GTM's Mehta as saying, "CIGS looks promising." If First Solar can execute in CIGS like they have in CdTe -- watch out. And if the president of the notoriously tight-lipped firm is on record talking up CIGS, they must be taking a serious look.
But it's early days in CIGS, and no real standard tool set has been established as in c-Si or even a-Si. There is no rich ecosystem of equipment and tool suppliers for this market and most every CIGS firm has a very different technique of building the CIGS product. Common techniques include sputtering, co-evaporation and electroplating-like processes.
So, new processes and technology enabling CIGS PV production are going to continue to emerge.
PyroPhotonics builds a new type of laser system that could improve yield, throughput and costs of the laser scribing process that is used in CIGS photovoltaics manufacturing. I spoke with Dr. Vittorio Fossati-Bellani, the VP of Sales and Marketing at the 20-person, VC-funded laser startup.
Manufacturers of thin-film solar cells often rely on three scribing processes (called P1, P2, and P3) to increase the operating voltage of the cells to useful values. These three scribes are critical to the overall efficiency of the cells, and their yield in manufacture is an important factor in determining the PV cell cost. (P1 acts on just Moly, P2 acts on Moly, CIGS and CdS while P3 includes the TCO.)
In many thin film manufacturing processes, laser scribing has become the preferred method.
However, CIGS has proven difficult to scribe with lasers, and mechanical scribing using a diamond needle is the most commonly employed process. Sophisticated ultrafast lasers have recently been demonstrated as a potential solution, but most CIGS manufacturers consider these lasers to be too expensive and not sufficiently robust for use in a 24/7 manufacturing environment.
PyroPhotonics has demonstrated a process that entails the laser scribing of CIGS materials using a programmable flexible pulsed laser. The company claims that their process produces clean scribes with no melting of the CIGS at the sidewalls, and leaves the Molybdenum layer undamaged. Additionally, they can also perform the P1 scribe in the difficult case of two-layer Molybdenum. Most commercial laser scribe processes can only scribe single-layer Molybdenum. The machine used in this process costs about $75,000.
The laser is of the Erbium-doped fiber laser variety, for those laser aficionados out there. It works at 1064 or 532 nanometers and has very fast rise and fall times. Unlike Q-switched and conventional fiber lasers, the pulse shape is fully programmable for pulse length, height and repetition rate, and can range from one nanosecond to 500 nanoseconds at one-nanosecond resolution. This allows the generation of arbitrarily shaped pulses or even multiple pulse bursts.
The startup is already working with a few CIGS companies. Their laser also has some application in Emitter Wrap Through hole drilling for c-Si applications. A lower power version is currently being sold to companies doing DRAM repair.
The firm is headquartered in Montreal with funding from Rho Ventures and Canada's BDC and EDC, and was founded in 2003.
As the CIGS market matures, we will start to see the processing and manufacturing supply chain mature, as well. PyroPhotonics is part of that maturation process. Other laser firms involved in various aspects of PV scribing include Coherent, Newport, Spectra-Physics and many others.
Examples of laser scribing using the PyroPhotonics Laser: