Black silicon: a nanostructured antireflection layer for solar cells

An Armenian company with profound experience in the field of designing and fabrication of solar systems has focused one of its research activities on developing high efficiency and low cost silicon solar cells by using nanostructured “black silicon”- BS.
One of the crucial problems in solar cells is that a significant part of the incoming radiation is reflected, which limits the efficiency of such devices.
One important way of minimizing this detrimental effect and  subsequently improving the conversion efficiency of solar cells is a reduction of the reflectance using an appropriate antireflection coating (ARC). 
However, even with these ARC the solar cells still - at best - lose 2 % to reflection and in case of e.g. multi-crystalline silicon up to 10 %. This calls for more efficient light absorbing technologies - preferably also at lower cost, which could lower the cost of producing solar cells in general.
The research is focused on developing high efficiency and low cost silicon solar cells by using nanostructured “black silicon”- BS. BS can be manufactured simply by adding a dense network of nanoscale needles on top of a standard silicon wafer. Modifying the material in this way makes it a lot less reflective, allowing solar cells that use it to trap light even when it's coming from very low angles. It was shown that there is a significant reduction of reflection index for BS with long densely packed needles at height of 650 nm. The efficiency of light detection is almost unchanged for the light flux with the angle of incidence up to 50°.
The company has  developed and patented a plasma etched method of BS formation, as well as proposed a new production process sequence of BS solar cells.
This technology is also compatible with current industrial fabrication of solar cells.
The company seeks for partners who would help to finalize the development of the technology up to commercial prototype for further commercial use/manufacturing under commercial agreement with technical assistance, technical cooperation agreement, research cooperation agreement .
The company seeks also  partners who would help with the finalization of the technology and set up large scale manufacturing of the product under manufacturing agreement.

The BS method exhibits some distinct advantages. First, it is a reliable and reproducible, yet self-organized process that does not necessitate any additionally applied mask. Second, the method leaves crystallographic intact nanostructure surfaces free of chemical contamination, in contrast, e.g., to structures obtained by wet etching. Third, it cannot only be applied to poly- and mono-crystalline wafers, but also to amorphous or crystalline Si thin films. 
Thus, BS texturing has the capacity to improve Si solar cells efficiency. The commercial viability of the technology is quite feasible, since the technology is scalable and inexpensive. This technology is also compatible with current industrial fabrication of solar cells.

Technology Readiness Level - 4.
The company has manufactured a BS as the anti-reflection coating on common (industrial) silicon solar cells. Measuring the IV-characteristics and the power conversion efficiency of the fabricated BS solar cell was performed. These solar cells present excellent anti-reflective behavior with a reflectance below R=2% in the spectral range of 580-1050 nm. This reflectance level is the best published in the literature to our knowledge, for BS layer obtained by plasma etched method.
Alpha-Testing of BS solar cells in the field conditions over the duration of different days were performed. The efficiency of solar cell samples have been significantly improved (8%), while the efficiency of light detection is almost unchanged for the light flux with the angle of incidence up to 50° This could be a good way to increase the yield of solar cells throughout the day.