All silicon tandem solar cell

Crystalline silicon is consistently the dominant material for commercial photovoltaic devices. Exploiting the direct and indirect bandgap of silicon results in a silicon-silicon tandem solar cells with possible efficiency benefits over standard single-junction silicon solar cells. Epitaxial growth offers a way to make such cells and the resulting devices have higher voltage and lower currents leading to much lower module losses. All silicon tandem devices were modeled in PC1D using precise solar spectrums generated with SMARTS. The optimal layer thicknesses found when the input spectrum is AM1.5G for a silicon-silicon device are: 3.3 μm for the top absorber and 172 μm for the bottom absorber. The modeled device produces an efficiency of 21.3%, a 1.1% relative increase over a model for a commercial silicon cell.