Antireflection properties and solar cell application of silicon nanostructures

Silicon nanowire arrays (SiNWAs) are fabricated on polished pyramids of textured Si using an aqueous chemical etching method. The silicon nanowires themselves or hybrid structures of nanowires and pyramids both show strong anti-reflectance abilities in the wavelength region of 300–1000 nm, and reflectances of 2.52% and less than 8% are achieved, respectively. A 12.45% SiNWAs-textured solar cell (SC) with a short circuit current of 34.82 mA/cm2 and open circuit voltage (Voc) of 594 mV was fabricated on 125 × 125 mm2 Si using a conventional process including metal grid printing. It is revealed that passivation is essential for hybrid structure textured SCs, and Voc can be enlarged by 28.6% from 420 V to 560 mV after the passivation layer is deposited. The loss mechanism of SiNWA SC was investigated in detail by systematic comparison of the basic parameters and external quantum efficiency (EQE)of samples with different fabrication processes. It is proved that surface passivation and fabrication of a metal grid are critical for high efficiency SiNWA SC, and the performance of SiNWA SC could be improved when fabricated on a substrate with an initial PN junction.