Monolithic Perovskite/Silicon Tandem Solar Cells on p-type POLO/PERC Silicon Bottom Cells

We report on proof-of-concept perovskite/silicon tandem solar cells on bottom cells featuring a polycrystalline silicon on oxide (POLO) front junction and a PERC-type passivated rear side with local aluminium-p+ contacts. We implement a process flow which is compatible with industrial, mainstream PERC technology. The top and bottom cells are connected via an indium tin oxide (ITO) layer, and the perovskite top cell is then monolithically integrated in a p-i-n architecture. The tunnel recombination junction between the two sub-cells, as well as the perovskite top cell are adapted from high efficiency perovskite/silicon heterojunction-based tandems. For the perovskite absorber layer, we use a mixed cation, mixed halide perovskite with a band gap of 1.68 eV. The proof-of-concept tandem cells demonstrate a power conversion efficiency (PCE) of 21.3%. We identify a potential for major performance enhancements by process and layer optimizations. Supported by optical simulations, we estimate a PCE potential of 29.5% for this tandem stack based on POLO/PERC bottom cells. Thus, we demonstrate that the large technology base of p-type PERC production has significant potential for an upgrade to highly efficient perovskite/POLO/PERC tandem solar cells.