Halogen anion pre-homogenization of sequentially deposited wide bandgap perovskites for commercial textured perovskite/silicon tandem solar cells

Abstract

An evaporation–solution sequentially deposited wide bandgap perovskite has been widely applied to fabricate efficient, commercial textured perovskite/silicon tandem solar cells. However, current works generally widen the bandgap by incorporating more bromine into organic salt solutions, which poses challenges for further broadening the bandgap of perovskite thin films and is also prone to inhomogeneous crystallization and component distribution. Here, a halogen anion pre-homogenizing (Pre-H) strategy is proposed by a pre-forming homogeneous inorganic halide precursor to narrow the nucleation rate disparity between the iodide and bromide components. This approach yields improved longitudinal crystallinity, enhanced compositional uniformity, and optimized bottom interfacial contact. In addition, augmenting the proportion of PbBr₂ in the precursor template enables bandgap expansion of the Pre-H perovskite up to 1.78 eV without phase segregation. Consequently, single-junction wide bandgap perovskite solar cells (1.68 eV) utilizing the Pre-H strategy achieve an impressive efficiency of 22.21%. The monolithic commercial textured perovskite/silicon tandem solar cell (1.05 cm²) attains an efficiency of up to 30.83%, featuring an open-circuit voltage (V_OC) of 1.945 V, the highest V_OC for perovskite/silicon tandem solar cells based on the sequential deposited perovskite to date. When scaled to 10.5 cm × 10.5 cm substrates, the encapsulated tandem device achieves a power conversion efficiency of 27.1% (certified as 26.6%, with an aperture area of 64.64 cm²).