Abstract

Unbalanced currents in serial-connected tandem solar cells are one of the major limitations for cost-efficient fabrication of third generation solar cells. By using optimized photon management, we will show for a micromoph solar cell that an embedded 3D photonic crystal acting as an intermediate reflector can balance the currents. It enhances experimentally the external quantum efficiency (EQE) for the current-limiting top cell up to factor of 3.6 corresponding to a short circuit current enhancement of about 25 % as compared to state-of-the-art textured micromorph solar cells. Our concept of 3D intermediate reflectors can be transferred to any other multi-junction solar cell even on textured substrates.

© 2011 Optical Society of America