State of Oregon

Robert K Graupner

James A Van Vechten

Ernest G Wolff

Tyrus K Monson

John R Arthur

An inexpensive, robust concrete solar cell (10) comprises a photovoltaic material embedded in and extending beyond front and rear major surfaces (18 and 16) of a matrix layer (14). The matrix layer typically comprises a high-strength, cementitious material, such as a macrodefect-free cement, reinforced with electrically nonconductive fibers (54) distributed throughout the matrix layer. The photovoltaic material comprises particles (12) of high-resistivity single crystal silicon, typically ball milled from ingot sections unsuitable for slicing into silicon wafers. An aluminum sheet (28) attached to the rear major surface provides electrical contact to one of two electrical region (22 and 24) of the semiconductor particle, and a translucent conductive layer (30) on the front major surface provides electrical contacts to the second electrical region. Overlapping electrically conductive reinforcing fibers (52) are embedded at the front major surface of the matrix layer to decrease the sheet resistivity of the surface and to inhibit the formation of surface cracks. Digitated electrode (32) further improves surface conductivity for conducting current off the cell. A voltage is generated between the two conductive layers when light incident on the semiconductor particles through the translucent conductive layer creates charge carriers that are propelled toward the conductive layers by a built-in field.

Concrete solar cell

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.

Growing community of inventors

Portland, OR, United States of America

Robert K Graupner