Polka dot concentrator cell

The silicon Polka Dot solar cell achieves high efficiency under concentrated illumination by eliminating grid shadow and having low reflection and series resistance losses. Present cells are 2 cm square with the front selectively etched to produce a 60 × 60 array of pyramidal indentations which penetrate through the cell, creating interconnect openings that permit photocurrent collected at the front junction to pass through to metallized electrodes on the back. A cover slip is bonded to the front using a medium which fills the indentations and reduces reflection losses. The back has two sets of interdigitated N⁺and P⁺fingers. One set joins the front diffused layer through the interconnect openings, which occupy <1% of the cell area. The other set contacts the interior. Initial cells without AR have achieved 18% efficiency at 10 suns.