Emitter Passivation of Silicon Solar Cell via Organic Coating at Room Temperature

by Michael Crowley

Silicon photovoltaics are a proven sustainable energy solution and take up 90% of the solar cell market. Silicon cells have many practical advantages associated with them, including high cell efficiency, stability and longevity. They are also extremely cost effective. The cost of mass produced silicon cells has dropped below $1/W, in some cases as low as $0.3/W. At the same time, efficiency continues to increase to 20%. The biggest hindrance to further increases in efficiency are high rates of recombination at the surface of the cells, which is what Shinde et. al (2016) have been working on.

In order to lower the rates of recombination, the technique of passivation has been employed. SiNx and SiO2 compounds have been used for passivation in the past. Although the desired surface passivation is accomplished, these compounds require high process temperatures (300° – 1000° C). At these temperatures, the properties of the silicon crystalline structure are affected. If these temperatures are reduced, efficiency and longevity are expected to increase.

To combat high process temperatures, new techniques have been presented. It has been shown that passivation can be achieved by using Si-O and Si-H and organic passivation. Shinde et. al (2016), look at passivation of n-type emitter by organic cover layer Oleylamine (OLA). This passivation technique will increase efficiency and has the ability to be processed at room temperature. Continue reading

Ion Implant Technology and ITS Applications to Solar Cells

by Michael Crowley

The once assumed fact, that Photovoltaic (PV) solar technologies could not be cost effective and energetically viable, is slowly crumbling. Relatively low-cost and powerful solar cells are produced in large quantities throughout the world, making the levelized cost of electricity (LCOE) of these cells competitive with other energy-related technologies. A similar thought process was assumed when discussing the possibilities for ion implant technology in solar applications. This assumption is slowly being proven wrong too. Ion implanting technology is slowly becoming a favorable method for doping formation in semiconductors (silicon is commonly used in present PV cells). By using this technique, higher-efficiency solar cells can be mass produced. Two hurdles must be faced in order to make this technology more accessible: high costs and low throughput. These hurdles have been faced most head on by a semiconductor company, Kingstone. By developing a simpler ion implanter, Kingstone believes they can cut 90% of their current operations cost while producing a very high thoroughput (>1500 wafers/hour). Continue reading