UV-Visible Light-Trapping Structure of Loosely Packed Submicrometer Silica Sphere for Amorphous Silicon Solar Cells

Abstract

We synthesized a loosely packed submicrometer silica-sphere (LPSS) monolayer at room temperature and used the LPSS monolayer as the frontside light-trapping structure for n-i-p-type amorphous Si (a-Si) solar cells (SCs) to improve photovoltaic characteristics of the cells. The frontside LPSS monolayer plays a role as a UV-visible light scatter and a broadband antireflector; both can greatly improve the photoresponse of the underneath a-Si adsorbed layer. When the filling density of the LPSS layer is optimized to 65%, the enhancement in the photocurrent and conversion efficiency of the 120 degrees C-fabricated SCs is as high as similar to 15% and similar to 6.9%, respectively. Accordingly, such an LPSS light-trapping structure boosts efficiency of 120 degrees C- and 140 degrees C-fabricated cells to 7.3% and 8.5%, respectively. Since the LPSS structure has a graded refractive index profile, it behaves like a nearly omnidirectional antireflector, enhancing solar efficiency at a very large incident angle of illumination.