Making surfaces water-repellent with sandpaper

In solar cell technology, surface texturing is essential for reducing the reflectance of cell surfaces and increasing their efficiency. This study employs photo-assisted electrochemical etching (PAECE) to fabricate a hybrid structure comprising a reversed pyramid structure and a high aspect ratio macro-pore on the silicon wafer surface, to reduce cell surface reflectance. The experimental results show that the etching depth of the fabricated macro-pore array structure was approximately 67.1 μm and its diameter was approximately 5 μm on the 525-μm-thick sample, such that the aspect ratio of the pore was approximately 13.4:1. The mean reflectance of a blank silicon wafer is 37.4% in the wavelength range of 280–800 nm; however, the reversed pyramid created using a 120-min PAECE process and 25-min RIE can reduce the mean reflectance to 0.7% on the 380-μm-thick sample. The novel fabrication process developed in this study is low cost and the hybrid structure can be applied to antireflection structures in single crystalline silicon solar cells.