Femtosecond Laser Ablation (fs‐LA) XPS Depth Profiling of Lead Halide Perovskite Thin Film Solar Cells

ABSTRACT Mixed organic–inorganic halide perovskites are finding strong interest as thin film solar cell materials. XPS depth profiling of a spin‐coated (FAPbI 3 ) 0.95 (MAPbBr 3 ) 0.05 perovskite thin‐film solar cell, has been performed. Profiles have been recorded using traditional monatomic and cluster ion beam bombardment and compared to those obtained using a new femtosecond laser ablation (fs‐LA) approach. The femtosecond laser employed has a wavelength of 1030 nm and a pulse length of 160 fs. Monatomic and cluster ion sputter depth profiling of the halide perovskite results in preferential sputtering of C, N and I and the appearance of Pb 0 in the Pb 4f spectrum as a preferential sputtering artefact. fs‐LA depth profiling is shown to retain the original composition and chemical state information of the perovskite layer with no chemical damage. An ablation rate of ≈33 nm through the perovskite layer was found at an incident laser energy of 42 μJ per pulse. A combined fs‐LA/monatomic sputtering depth profile enabled all layers in the cell to be identified whilst retaining the true composition of the perovskite layer.