Fabricating efficient and stable quasi-3D and 3D/2D perovskite solar cells with 2D-sheets connected by inorganic type...

In this work, we report a novel two-dimensional (2D) (SrBr)₂PbI₄perovskite layered architecture, which were formed by the reaction of strontium bromide (SrBr₂), strontium iodide (SrI₂) and lead iodide (PbI₂). Formation of 2D (SrBr)₂PbI₄was verified by small angle XRD peak at 6.4°, which corresponds to the layer distance of 13.78 Å. The best one of solar cells fabricated with Quasi-3D perovskite, (SrBr)₂FA₅₉Pb₆₀I₁₈₁(n= 60), showed a power conversion efficiency (PCE) of 18.46% and retained 95% of the initial PCE at 1000 h in the dry air. Further, the 2D (SrBr)₂PbI₄as the surface passivation layer on the 3D FAPbI₃perovskite greatly reduced the defects at the perovskite/Spiro-OMeTAD interface, and the corresponding solar cells with FAPbI₃/(SrBr)₂PbI₄3D/2D structure achieved a PCE of 22.14% and over 90% retention of the original PCE at 1000 h. In short, this work provides an example of inorganic complex cations that can form 2D perovskites and achieve perovskite solar cells with high PCE and stabilization at the same time.