Low-cost solar cells based on large-area unconventional silicon

Low-cost approaches to solar cell manufacture require the use of inexpensive low-grade nonsingle crystalline silicon. Earlier experimental results indicate that conventional polysilicon, as it is used as ingot for the single crystal growing process, leads to solar cells of poor photovoltaic performance. These problems were overcome by utilizing unconventional nonsingle crystalline silicon, which is characterized by controlled size and structure of the individual grains. With modified processing, optimized in respect to the unique structure of the material, large-area solar cells could be realized under production scheme methods. Cells exhibiting dimensions up to 11 cm × 11 cm were fabricated, AM0 efficiencies of 8 percent could be achieved corresponding to AM1 values exceeding 10 percent. On test samples of 2 cm × 2 cm area AM0 efficiency Of 12.5 percent (AM1 value equivalent 14.0 percent) could be reached. The new material together with the optimized processes offer potentials for significant cost reduction by virtue of their being applicable to volume production and to automated fabrication techniques.