Ultrathin crystalline silicon (c-Si) solar cells, which are of several micrometers thick, have attracted much attention in recent years, since it can greatly save raw materials than the traditional ones. To enhance the absorption, as well as to improve the cell efficiency, of the ultrathin c-Si, light trapping nanostructures are used to increase the effective absorption length to close to the 4n² of the materials thickness, which is determined by the Lambertian limit. Here, we propose a novel interlaced semi-ellipsoid nanostructures (ISENs) to improve the performance of ultrathin c-Si solar cells. In this structure, the large and small periods in x and y direction can improve the light trapping capability at long and short wavelengths respectively. Meanwhile, the graded refractive index of the surface can act as the antireflection coating. By optimizing the ISENs, the short circuit current density of 30.15mA/cm² was achieved by simulations for a 2 μm thick c-Si solar cell with r_x = 500 nm, r_y = 200 nm, r_z= 550 nm and without antireflection coating and metal back reflector. The absorption is close to 87% of the Lambertian limit with equivalent thickness. We expect this structure can be fabricated by low cost nanosphere lithography technology and used to improve the efficiency of the ultrathin c-Si solar cells.

Date Published: 15 October 2015
PDF: 6 pages
Proc. SPIE 9672, AOPC 2015: Advanced Display Technology; and Micro/Nano Optical Imaging Technologies and Applications, 96720H (15 October 2015); doi: 10.1117/12.2199336

Published in SPIE Proceedings Vol. 9672:
AOPC 2015: Advanced Display Technology; and Micro/Nano Optical Imaging Technologies and Applications
Byoungho Lee; Yikai Su; Min Gu; Xiaocong Yuan; Daniel Jaque, Editor(s)