Photon management with inverse-designed multilayers for Type-II CdTe/CdZnSe quantum dot intermediate band solar cells

We develop and optimize broadband, wide-angle, aperiodic multilayer reflectors operating in the near-infrared to enhance the performance of Type-II quantum dot (QD) intermediate band solar cells (IBSCs). Using rigorous optimization techniques, we perform the inverse-design of the multilayer stack under various configuration constraints. CdTe/ZnCdSe submonolayer QDs IBSC grown on InP is used as an illustrative example, for which we demonstrate upwards of a 64% enhancement in the QD absorption. The optimal structure consists of a 60-pair ZnCdSe/ZnCdMgSe multilayer reflector which is well lattice-matched to the substrate. This structure is shown to be highly resilient to material imperfections and feature size deviations, ensuring robustness in practical manufacturing scenarios. The discussed design strategies can be implemented for other types of solar cell technologies and applications where light-trapping and recycling are crucial for improving efficiency.