Nanopatterned SiNx Broadband Antireflection Coating for Planar Silicon Solar Cells
Crystalline Si solar cells based on thin wafers, with thicknesses in the range of 5–50 μm, can find applications in a wide range of markets where flexibility and bendability are important. For these cells, avoiding standard macroscopic texture is desirable to increase structural integrity. Herein, a nanopatterned SiNx antireflection (AR) coating that consists of 174 nm-radius and 118 nm-high SiNx nanodisks arranged in a square lattice on a thin (59 nm) SiNx layer is introduced. This geometry combines Fabry–Pérot AR and forward scattering by a resonant Mie mode to achieve high transmission into the Si absorber over a broad spectral band. The nanostructured coating is patterned on a commercial interdigitated-back-contact (IBC) Si solar cell, experimentally demonstrating a short-circuit current density (J sc) of 36.9 mA cm−2, 2.3 mA cm−2 higher than for a single-layer AR coated cell, and an efficiency of 16.3% at a thickness of around 100 μm. It is shown that light incoupling efficiency is comparable to that of pyramidal texturing, while the absorption in the infrared is lower, due to less-effective light trapping. Overall, nanopatterned SiNx broadband AR coatings are an appealing option for improving light management in ultrathin solar cells and other optoelectronic devices.