Efficient nanostructured ‘black’ silicon solar cell by copper-catalyzed metal-assisted etching

Abstract

We produce low-reflectivity nanostructured ‘black’ silicon (bSi) using copper (Cu) nanoparticles as the catalyst for metal-assisted etching and demonstrate a 17.0%-efficient Cu-etched bSi solar cell without any vacuum-deposited anti-reflection coating. The concentration ratio of HF to H2O2 in the etch solution provides control of the nanostructure morphology. The solar-spectrum-weighted average reflection (Rave) for bSi is as low as 3.1% on Cu-etched planar samples; we achieve lower reflectivity by nanostructuring of micron-scale pyramids. Successful Cu-based anti-reflection etching requires a concentration ratio [HF]/[H2O2] ≥ 3. Our 17.0%-efficient Cu-etched bSi photovoltaic cell with a pyramid-texture has a Rave of 3% and an open circuit voltage (Voc) of 616 mV that might be further improved by reducing near-surface phosphorus (P) densities