Efficiency improvement in Si thin film solar cells by employing composite nanocone-shaped grating structure

Abstract

The improvement in both the light absorption and energy conversion efficiency for thin film silicon solar cells by employing Al2O3/Si or SiN/Si composite nanocone-shaped gratings (CNCG) is theoretically studied. Our results show that the enhancement of the absorption and efficiency for Si thin film solar cells decorated by CNCG is mainly dominated by the nanocone-shaped gratings, but slightly fluctuated with the dielectric cladding layer and its thickness. The performance improvement is more significant using SiN/Si CNCG than using Al2O3/Si CNCG. The highest conversion efficiency of 6.60 and 9.53% are achieved in 1-µm-thick solar cells with SiN (120 nm)/Si CNCG and 2-µm-thick Si solar cells with SiN (90 nm)/Si CNCG respectively, which are compared to the conversion efficiencies of 3.23 and 3.96% for their planar counterparts. When the surface passivation effect is considered, the conversion efficiency should be enhanced more.