The new patent filing covers several advanced methods to perform a high-quality black etch on silicon, including procedures to properly handle substrates and stabilize the proprietary fluids used in the process. Careful control of these aspects enables achieving both the necessary consistency of the black silicon etching process and the manufacturing speed needed for insertion into a solar cell production line.
Importantly, a key feature of Natcore’s process is the fact that it is single-sided, even though it is performed in mild conditions without the need for vacuum. Thus, only the front of the wafer is black-etched, applying the antireflection properties exclusively where they are needed. This is important for all advanced solar cell structures now under development by manufacturers.
Companies are looking for ways to reflect not only light away from the back surface of the cell but also minority carriers (i.e., electrons for standard-type cells). Reflecting the light back into the cell will allow for more of it to be absorbed, and reflecting the minority carrier electrons away from the back contact enables more of them get to the upper metal contact. Both effects improve the output of the cell.
Natcore’s patent pending one-side processing greatly expands the Company’s market opportunities to include all single crystal and multicrystal silicon cell manufacturers as they put their advanced cell designs into manufacturing. That will include cells with all back contacts, improved n-on-p cell structures and p-on-n cell structures.
A front-surface-only black is also the ideal starting point for the innovative laser-based production processes the Company is now developing.
“Every day in our labs, our scientists and technicians are hard at work optimizing our black silicon production process — making it even faster and more uniform, and building prototype equipment to demonstrate the best process,” notes Chuck Provini, Natcore’s president and CEO.
We sometimes forget ourselves how revolutionary our process is, and are now getting very positive feedback from our research partners at major universities and independent labs. It is clear that our side-selective process is compatible with many high efficiency cell structures, and establishes a solid foundation for future advances in black silicon solar cells.
An Exciting Antibacterial Application
For Black Silicon
In addition to their work on black silicon and laser processing in the Rochester labs, Natcore’s scientists, in collaboration with Prof. Andy Barron’s research group at Rice University, are now also researching the application of black silicon as an antibacterial surface.
As recently reported in the journal Nature Communications, a group headed by microbiologist Elena Ivanova of Swinburne University of Technology in Australia has discovered that black silicon surfaces can act as effective biocides, with the sharp, “nanopillar” structure proving to be highly lethal to certain human pathogens.
The potential for a black silicon biocidal surface, if it can be manufactured and transferred to other surfaces, is exceptional. For example, the evolution of drug-resistant microbes is a growing concern in medicine. But a surface that physically destroys microbes by deforming or destroying their cell walls — as black silicon is proving it can do — will completely sidestep the ability of microbes to develop drug resistance.
While the effectiveness of black silicon as a biocide has been indicated by this research, the ability to manufacture appropriately-structured black silicon in quantity remains elusive. Because this is precisely where Natcore excels, the Company’s scientists are now specifically targeting this application in ongoing research.
The Company will promptly announce new advances in this area as they are achieved and protected.