Abstract
Realization of colloidal quantum dot (CQD)/organic photovoltaic (OPV) tandem solar cells that integrate the strong infrared absorption of CQDs with large photovoltages of OPVs is an attractive option toward high-performing, low-cost thin-film solar cells. To date, monolithic hybrid tandem integration of CQD/OPV solar cells has been restricted due to the CQD ink's catastrophic damage to the organic subcell, thus forcing the low-band-gap CQD to be used as a front cell. This suboptimal configuration limits the maximum achievable photocurrent in CQD/OPV hybrid tandem solar cells. In this work, we demonstrate hybrid tandem solar cells employing a low-band-gap CQD back cell on top of an organic front cell thanks to a modified CQD ink formulation and a robust interconnection layer (ICL), which together overcome the long-standing integration challenges for CQD and organic subcells. The resulting tandem architecture surpasses previously reported current densities by, similar to 20-25% and yields a state-of-the-art power conversion efficiency (PCE) of 9.4%.