(311g) Scalable Non-Lithographic Approach To Fabricate Wafer-Scale Subwavelength Surface Textures For Improving The Conversion Efficiency Of Silicon Solar Cells

Current production of solar cells is dominated by crystalline silicon modules; however, due to the high refractive index of silicon, more than 30% of incident light is reflected back, which greatly reduces the conversion efficiency of photovoltaic devices. Surface texturing has become a common practice for Si solar cells, and, in combination with vacuum deposited antireflection coatings (ARCs), reduces reflection losses to a few percent. Unfortunately, the high cost of vacuum deposition of ARCs is a big challenge for economic production of large photovoltaic panels. Here we present a simple yet scalable non-lithographic approach to fabricate subwavelength surface textures for improving the conversion efficiency of crystalline silicon solar cells. Wafer-scale, crystalline arrays of inverted pyramids with adjustable geometries, which directly function as efficient moth-eye ARCs, are anisotropically etched in silicon substrates by using templated metallic nanohole arrays as etching masks. These periodic nanoholes are replicated from non-close-packed monolayer colloidal arrays made by a simple spin-coating technique. Our optical measurements and theoretical calculations show that the pyramidal moth-eye ARCs can reduce the reflectivity by one order of magnitude for a wide wavelength range.