Absorption Enhancement in Ultrathin Crystalline Silicon Solar Cells with Antireflection and Light-Trapping Nanocone Gratings

Ken Xingze Wang†, Zongfu Yu‡, Victor Liu‡, Yi Cui§, and Shanhui Fan*‡

^†Department of Applied Physics, ^‡Department of Electrical Engineering, and ^§Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States

 Stanford Institute for Materials and Energy Sciences,SLAC National Accelerator Laboratory, Menlo Park, California 94205, United States

Nano Lett., Article ASAP

DOI: 10.1021/nl204550q

Publication Date (Web): February 22, 2012

Copyright © 2012 American Chemical Society

Enhancing the light absorption in ultrathin-film silicon solar cells is important for improving efficiency and reducing cost. We introduce a double-sided grating design, where the front and back surfaces of the cell are separately optimized for antireflection and light trapping, respectively. The optimized structure yields a photocurrent of 34.6 mA/cm2 at an equivalent thickness of 2 μm, close to the Yablonovitch limit. This approach is applicable to various thicknesses and is robust against metallic loss in the back reflector.