Broadband light harvesting enhancement with front double and back metallic gratings in thin film solar cells

In this paper, a-Si based thin film solar cells combined with front double dielectric and back triangle metallic gratings are proposed to enhance light harvesting in broadband wave range and wide-angle incident. The grating diffraction effect of front dual dielectric gratings and surface plasmon polaritons (SPPs) induced by back metal gratings promote the total optical absorption. We achieve 93.7% light absorption in TM incident and 91.4% average harvesting (on TE and TM hybrid mode) by the optimized structure in the spectrum range from 300 to 800 nm, about 20% enhancement. And the short circuit photocurrent density is up to 22.4 mA/cm2 with 10% increase.