Shell thickness effects on core-shell c-Si/a-Si nanopillar solar cells

The light harvesting properties have been numerically investigated in c-silicon/a-silicon core-shell nanopillar array. The influence of shell thickness on optical absorption versus different core diameter has been thoroughly analyzed by using finite-difference time-domain (FDTD) simulations. It is found that a-silicon shell significantly enhanced infrared absorption especially for smaller diameter nanopillar. As a result, the core-shell nanopillar device exhibits a absorption enhancement from 0.22 to 0.65 at 800nm and from 0.05 to 0.43 at 1000nm. Furthermore, the mechanism of the absorption has been discussed.