Concrete solar cell

Abstract

An inexpensive, robust concrete solar cell (10) comprises a photovoltaic material embedded in and extending beyond the major surfaces (16 and 18) of a matrix layer (14). The matrix layer typically comprises a high strength, cementitious material, such as a macrodefect free cement. The photovoltaic material comprises particles (12) of high-resistivity single crystal silicon, typically ball milled from ingot sections unsuitable for slicing into silicon wafers. The ingot sections include unprecipitated dissolved oxygen that is electrically activated by a low temperature annealing process to produce n-type silicon, even in silicon crystals that include a p-type dopant. An aluminum sheet (28), positioned on the backside of the matrix layer, is briefly melted together with the silicon particles to produce a p-type aluminum-doped silicon region (22) that forms a pn junction with the n-type region (24) of the particle. The aluminum sheet also provides the electrical contact to the p-type regions. The front surface of the matrix layer, from which the n-portion of the silicon particle protrudes, is covered with a translucent indium tin oxide conductive layer (30) that provides electrical contacts to the n-portion of the pn junction and digitated electrode (32) for conducting current off the cell. A voltage is generated between the two conductive layers when light incident on the photovoltaic particle through the indium tin oxide conductive layer creates charge carriers.