Photovoltaic cell fabricated using nanoporous black silicon synthesized via aluminium-assisted chemical etching

In this work, a photovoltaic (PV) cell fabricated using nanoporous black silicon (bSi) synthesized via an aluminium-assisted chemical etching (AACE) process is demonstrated for the first time. To fabricate the PV cells, n-emitters are diffused into the p-type planar crystalline silicon (cSi) and nanoporous bSi substrates to form pn-junctions, followed by the deposition of metal contacts (i.e., silver-grid as front contact and aluminium as back contact). The highest average power conversion efficiency (η _avg) of 18.62% is obtained from the PV cell fabricated using the nanoporous bSi sample with the lowest average reflection of 5.7% within the 300-1100 nm wavelength region. This efficiency represents an enhancement of 169% when compared to the average efficiency of 6.93% for the reference planar cSi PV cell fabricated under similar conditions. The significant efficiency improvement is attributed to the superior broadband light trapping by the nanoporous bSi surface, which effectively suppresses optical reflection across a wide spectral range. The power conversion efficiency of the bSi PV cell will be further enhanced by incorporating an ARC and a passivation material on the device.