High performance porous silicon solar cell development

We have fabricated Si solar cells from porous Si/bulk Si structures. Two cell types, having the junction within the porous Si or within the bulk Si, were studied. We have seen clear evidence of the photovoltaic effect in porous Si, although currents and voltages are low, due to spreading resistance problems. On a non-AR-coated bulk Si p-n junction solar cell, formation of a porous Si surface layer increases both internal- and external quantum efficiency (QE) by functioning both as a light-trapping antireflection coating and an effective minority-carrier mirror. Current-voltage (I-V) data indicate that the porous Si layer does not lead to an increase in dark current.