Successful passivation of the surface of black silicon solar cells using liquid phase deposition (LPD) method has been demonstrated by Natcore Technology researchers. The research has been going on for a number of years to enhance the performance of the black silicon cells.
The visible color of a silicon wafer surface after the etching process has been carried out with nanopores is referred as black silicon. Normally, the etched silicon cell surface has 40% reflectivity and offers a glossy look to the wafer. With the addition of antireflective coating, the average reflectivity decreases to roughly 6%, providing unique dark blue colour to the solar cells. Scientists from Natcore, National Renewable Energy Laboratory (NREL) and Rice University have demonstrated that the black silicon technique lowers the average silicon cell surface reflectivity to 1.5% or lower.
The result of the combined study, sponsored by Natcore, has shown that there is a 20-fold increase in minority carrier lifetime of black silicon solar cell surface coated with LPD process when compared to an uncoated surface. This will enable significant power gains compared to standard production cells.
Passivation refers to the process of loading the hanging atomic bonds on the solar cell surface and decreasing the defects in the cell’s upper area. The process is important for high performance, long-term silicon cell production. Natcore’s LPD successfully passivates black silicon and also removes the requirement for thermal oxidation. The company is currently discussing with NREL and other industries to speed up the advancements in the black silicon passivation process.
Source: http://www.natcoresolar.com/