Silica nanospheres as back surface reflectors for crystalline silicon thin‐film solar cells

In this paper, fabrication of a non‐continuous silicon dioxide layer from a silica nanosphere solution followed by the deposition of an aluminium film is shown to be a low‐cost, low‐thermal‐budget method of forming a high‐quality back surface reflector (BSR) on crystalline silicon (c‐Si) thin‐film solar cells. The silica nanosphere layer has randomly spaced openings which can be used for metal‐silicon contact areas. Using glass/SiN/p + nn + c‐Si thin‐film solar cells on glass as test vehicle, the internal quantum efficiency (IQE) at long wavelengths (>900 nm) is experimentally demonstrated to more than double by the implementation of this BSR, compared to the baseline case of a full‐area Al film as BSR. The improved optical performance of the silica nanosphere/aluminium BSR is due to reduced parasitic absorption in the Al film. Copyright © 2007 John Wiley & Sons, Ltd.