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