Soitec has announced the industry’s first four-junction solar cell for concentrator photovoltaic (CPV) systems, entering the industry’s roadmap at a world-class level with 43.6 % efficiency. Soitec is best known as the world’s leading producer of SOI wafers for microelectronics. For the new generation of optimized III-V-based multi-junction solar cells, Soitec has leveraged its proprietary semiconductor-bonding (Smart Stacking™) and layer-transfer (Smart Cut™) technologies and collaborated with Fraunhofer and Leti.
Soitec’s CPV modules are built on Concentrix technology, using Fresnel lenses to concentrate sunlight 500 times and focus it onto the tiny, highly-efficient multi-junction solar cells. Different types of solar cells are stacked on top of one another, with each cell type designed to convert a certain range of the solar spectrum: short wave radiation, medium wave radiation and infrared. The current generation of this technology is triple junction, achieving module efficiency of 30% — almost twice as high as the efficiency of conventional silicon photovoltaic modules.
To reach 43.6 % efficiency, Soitec’s innovative new four-junction cell uses two new, highly sophisticated dual-junction sub cells grown on different III-V compound materials, which allows optimal band-gap combinations tailored to capture a broader range of the solar spectrum. This maximizes energy-generating efficiency, and puts the company on track to be the first to reach the target of a 50% cell efficiency level.