Improving the Solar Cell Efficiency by Applying Two Dimensional Self-Assembled Nanoparticle Arrays

For solar cells, it is generally thought that surface reflectivity is one of the bottlenecks that limited the conversion efficiency. Tremendous efforts have been spent on reducing the reflectance using different structures to trap more photons in the solar cells.
In this thesis, nanopatterned photodiodes are found to have faster transit time and lower reflectivity. The nanopatterns are made by nanosphere lithography. Silica nanoparticles were then coated on the solar cell surface without altering the whole structure. It’s a more practical method for the industry purpose which would not like the complicated processes involved. The two dimensional nanoparticle arrays improve the efficiency not only at normal incidence but also at oblique incidence. The improvements are attributed to the guided modes excited by the two dimensional silica grating structure and the reduction of the reflectivity.
Furthermore, we found the silica nanoparticles improve the TE polarized light more significant than TM polarized light, which is a good way to compensate the larger reflectivity in TE polarized light for oblique incidence. If the nanoparticles can be coated on a large area, it will have a profound effect on solar cells industry.