Halogen Anions Pre-homogenization of Sequential Deposited Wide Bandgap Perovskite for Commercial Textured Perovskite/Silicon Tandem Solar Cells

The evaporation-solution sequential deposited wide bandgap perovskite has been widely applied to fabricate efficient, commercial textured perovskite/silicon tandem solar cells. However, current works generally widened the bandgap by incorporating more bromine into organic salt solutions, which poses difficulties for enlarging the bandgap of perovskite thin films and is also prone to inhomogeneous crystallization and component distribution. Here, a halogen anions pre-homogenizing (Pre-H) strategy was proposed by pre-forming homogeneous inorganic halide precursor to narrow the difference in nucleation rates between the iodide and bromide components, which brings about an improved longitudinal crystallinity, compositional uniformity, and fine contact with the bottom interface. In addition, we found that augmenting proportion of PbBr2 in the precursor template enabled the bandgap of Pre-H perovskite to further expand to 1.78 eV without any phase segregation. Consequently, the single-junction wide bandgap perovskite solar cells (1.68 eV) utilizing the Pre-H strategy achieved an impressive efficiency of 22.12%. The monolithic commercial textured perovskite/silicon tandem solar cell (1.05 cm2) attained an efficiency up to 30.83%, featuring an open-circuit voltage (VOC) of 1.945 V, the highest VOC recorded for the perovskite/silicon tandem solar cells based on the sequential deposited perovskite to date. Upscaling the substrate to 10.5 cm × 10.5 cm, encapsulated tandem device achieved a power conversion efficiency of 27.1% (certified as 26.6%, with an aperture area of 64.64 cm2).