Segmented Multi-Junction Solar Cells: A New Opportunity for Cell Design & Optimization

Multi-junction solar cell design can be enhanced using a process of subcell segmentation, whereby each subcell is further sub-divided into multiple optically-thin pn junctions. This design increases output voltage, reduces current (and associated resistive losses), and crucially, adds a degree of freedom to achieve current-matching across segments (controlled by epitaxial layer thicknesses) rather than across subcells (controlled by material bandgap). This design expands the highest efficiency region of the bandgap design space, pivoting away from the need to obtain ideal bandgap combinations for the highest efficiencies.