Solar Cells on Multicrystalline Silicon Thin Films Converted from Low-Cost Soda-Lime Glass

Fabrication and characterization of solar cells based on multicrystalline silicon (mc-Si) thin films are described and synthesized from low-cost soda-lime glass (SLG). The aluminothermic redox reaction of the silicon oxide in SLG during low-temperature annealing at 600 - 650 degrees C leads to an mc-Si thin film with large grains of lateral dimensions in the millimeter range, and moderate p-type conductivity with an average Al acceptor concentration between 5 x 1016 and 1.2 x 1017 cm-3 in the bulk. A residual composite layer of mainly alumina and unreacted Al forms beneath the mc-Si thin film as the second product of the crystalline silicon synthesis (CSS) process, which can be used as rear contact in a vertical solar cell design. The mc-Si absorber (approximate to 10 mu m) is thin enough that the diffusion length given by a minority carrier lifetime of approximate to 1 mu s exceeds the path length to the top contact several times. Homojunction and heterojunction diodes have been fabricated on the mc-Si thin films and show great potential of CSS for the realization of high-performance solar cells. Multicrystalline silicon thin films from synthesized low-cost soda-lime glass (SLG) using aluminothermic reduction at 600 - 650 degrees C show moderate p-type doping of approximate to 1 x 1017 cm-3. Heterojunction solar cells exhibit an open-circuit voltage of 426 mV, a short-circuit current density of 7.29 mA cm-2, a fill factor of 52.3%, and a conversion efficiency of 1.6%. image