Core-shell structured Si/ZnO photovoltaics

Periodic Si pillar arrays synthesized by metal assisted chemical etching method exhibit an excellent light harvesting capability, ideal for core-shell structured solar cell applications. To investigate the photovoltaic prospective, a radial heterojunction device is fabricated by conformal coating a layer of Al doped ZnO film on the p-Si pillar array. This core-shell structure has achieved low reflectance (<12%) over a broad wavelength range, and has demonstrated more than doubled enhancement of the short-circuit current as compared to the traditional planar architecture. Although reverse recovery transient measurement shows that this device with no surface passivation has shorter minority carrier life time than the planar structure, the overall efficiency is enhanced. It suggests that device efficiency could be much improved through proper surface treatment. This renders a promising path for core-shell structured solar cell with higher efficiency yet reduced material per device element.