Performance optimization techniques for the front and back of nanostructured ‘black silicon’ solar cells

In this work we present techniques to improve the front and back surface performance of nanostructured black silicon (bSi) solar cells. Proximity doping using ammonium dihydrogen phosphate (ADP) is used to reduce the physical impact on the nanostructure of bSi during fabrication. Potassium hydroxide (KOH) is used to etch off the highly doped region of the front emitter. Forming gas anneal (FGA) is employed to reduce the series resistance and enhance surface passivation, improving cell efficiency by over 31%. The back-surface-field (BSF) formed by sputtered aluminum (Al) is optimized to reduce backside recombination rate, improving external quantum efficiency (EQE) by an average of 8.31% in the long wavelength region.