Effects of metallic nanodiscs on solar absorption in Si nanopillar array solar cell

In this paper the solar energy absorption characteristic of Si nanopillar (SiNP) array solar cell with metallic nanodiscs (NDs) is studied via simulation by finite-difference time-domain calculations. It seems that among the common metals including Au, Ag, Cu and Al, Cu is the best one for the enhancement of overall absorption. But it is further demonstrated that the additional absorption mostly comes from metal NDs which is useless for improving the performance of solar cells. Then we study the absorption of Si pillars and Si substrate separately, which indicates that metal NDs can enhance the absorption of Si pillars while decrease the absorption of Si substrate and the overall absorption is actually degraded. The mechanism of the absorption enhancement within the SiNPs is also discussed.