Buried PN junction nanopillar solar cell: A novel approach to reduce recombination loss in surface nanostructure

Nanopillar solar cells have recently attracted considerable attention due to their excellent light trapping property. So far, three types of pn junction structures have been studied for nanopillar cells: the planar deep-junction type, the planar shallow-junction type, and the radial junction type. However, they all suffer serious recombination loss in the heavily doped region of the nanopillar. Here we propose a “buried junction” pn junction nanopillar solar cell, in which the emitter is formed not in the nanopillar, but at the surface region of the substrate. Reduction of the recombination loss in the proposed structure is numerically demonstrated. The buried junction approach opens a new possibility to achieve high-efficiency surface nanostructured solar cells.