Silicon-Based Monolithic Triple-Junction Solar Cells with Conversion Efficiency >34%

Triple-junction solar cells with top cells made from III-V compound semiconductors on a silicon bottom cell show conversion efficiencies beyond the theoretical limit of single-junction devices, so this is one of the promising technologies for terrestrial photovoltaics. In this work, a III-V//Si tandem device with 34.5% efficiency is presented and further developments are discussed. A detailed investigation of the silicon bottom cell revealed, that with optimum wafer resistivity (~1 Ω cm) and low-temperature passivation of the cell perimeter, the perimeter losses can be reduced to ~0.2%abs. This corresponds to an efficiency gain of up to 0.8%abs for the current devices.