Dry-wet hybrid deposition of wide-bandgap mixed-halide perovskites for tandem solar cell applications

The tandem architecture of solar cells is expected to be one of the promising strategies for further improving the performance of photovoltaic devices. While a dry-wet hybrid deposition method is highly promising for fabricating perovskite top cells on textured silicon bottom cells, the bandgap tunability of this deposition method has not been investigated in detail. Here, we show the systematic investigation on mixed-halide perovskite films fabricated by the dry-wet hybrid deposition method on a PbBr2 underlayer. The thermally deposited PbBr2 underlayer is demonstrated to be beneficial for promoting reaction with an organic halide precursor solution, resulting in a dense morphology with large perovskite grains. Furthermore, the hybrid deposition method is also shown to be a straightforward way for wide-range bandgap tuning as it can facilitate halogen mixing. These findings provide useful guidelines for further improving the power conversion efficiency of multijunction tandem solar cell devices.