Wave-shaped Si crystal wafers obtained by plastic deformation and preparation of their solar cells

We can prepare wave-shaped crystal wafers by the plastic deformation of Si crystal wafers, and we report on the characteristics of solar cells fabricated using the wave-shaped Si wafers, in order to demonstrate whether the shaped wafers are of high quality to be used in the preparation of devices or not. To obtain wave-shaped Si wafers, graphite dies were used. The diameter of the convex and concave waves formed in the dies is 4 mm. The Si wafers were pressed by an overload of 200 N. A thickness versus temperature region for obtaining well wave-shaped Si wafers by plastic deformation was determined. Solar cells were prepared using wave-shaped wafers pressed at 1100 and 1200°C. The wafers were annealed at 1109 and 1209°C, respectively, for 1 h in a hydrogen atmosphere. The conversion efficiency of the wave-shaped solar cells is 6.0%-10.1%. Thus, it is clarified that the wave-shaped wafers are of high quality to be used in the preparation of devices. The quality of the wafers can be significantly improved by suitable thermal treatments.