Low-Pressure Vapor-Assisted Solution Process for Thiocyanate-Based Pseudohalide Perovskite Solar Cells

In this report, we fabricated thiocyanate-based perovskite solar cells with low-pressure vapor-assisted solution process (LP-VASP) method. Photovoltaic performances are evaluated with detailed materials characterizations. Scanning electron microscopy images show that SCN-based perovskite films fabricated using LP-VASP have long-range uniform morphology and large grain sizes up to 1 μm. The XRD and Raman spectra were employed to observe the characteristic peaks for both SCN-based and pure CH₃NH₃PbI₃ perovskite. We observed that the Pb(SCN)₂ film transformed to PbI₂ before the formation of perovskite film. X-ray photoemission spectra (XPS) show that only a small amount of S remained in the film. Using LP-VASP method, we fabricated SCN-based perovskite solar cells and achieved a power conversion efficiency of 12.72 %. It is worth noting that the price of Pb(SCN)₂ is only 4 % of PbI₂. These results demonstrate that pseudo-halide perovskites are promising materials for fabricating low-cost perovskite solar cells.