A bi-layer anti reflection coating (ARC) composed of MgF2-Ta2O5 was designed using a rigorous mathematical approach and was experimentally tested on a commercial grade solar cell as a proof of concept that the coating can be applied to multi-junction solar cells. A reactive sputter process was used to sputter tantalum oxide and a thermal evaporation process was used for depositing magnesium chloride. The thickness values of each film were measured via profilometry, elipsometry, and reflectometry techniques. Elipsometry was also used to determine the film material’s respective index of refraction. Diffuse field reflectance measurements of each film were made using an integrated sphere reflectometer for wavelengths ranging from 400 nm to 700 nm. The ARC was then deposited on a commercial c-Si solar cell (SC) and compared to the same solar cell without the bi-layer ARC. This resulted in a decrease in average reflectivity of 11% on the textured cell surface and an increase in external quantum efficiency (EQE) by 7% for light with wavelengths from 400 nm to 700 nm when the ARC was present.
Mafrici, Dylan J.
"MgF2/Ta2O5 Anti Reflective Coating for 3rd Generation Solar Cells,"
Journal of the Microelectronic Engineering Conference: Vol. 22
, Article 16.
Available at: http://scholarworks.rit.edu/ritamec/vol22/iss1/16