Insights into (Cs0.22FA0.78)Pb(I0.85Br0.15)3 Triple Halide Perovskite films: Stability Investigations via Angle-Resolved XPS Analysis
Date
2024-04
Authors
Mahamudujjaman, Md
Scolfaro, Luisa M.
Geerts, Wilhelmus J.
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Abstract
Perovskite materials have garnered significant attention from researchers due to their promising photovoltaic properties and cost-effective production processes. These films can be deposited using solvent-based techniques close to room temperature, such as spin-casting, blade-coating, slot-die printing, and inkjet printing. Triple halide perovskites, with their tunable wide bandgap, offer promising applications in tandem solar cells, particularly when paired with silicon-based cells. Despite their enhanced efficiencies and reduced production costs, the commercial viability of perovskite solar cells remains constrained by their limited stability. In our study, we employed angle-resolved X-ray photoelectron spectroscopy (XPS) to examine a spin- coated absorber layer formulated from (Cs0.22FA0.78)Pb(I0.85Br0.15)3 with an added 3 mol % MAPbCl3, also referred to as Cs22Br15. The inks, based on DMF, were prepared in a glovebox, and applied to plasma-cleaned glass substrates. Following deposition, the wet films were annealed at 100°C for 30 minutes. X-ray diffraction (XRD) analysis revealed that the annealed samples transitioned to a photo-active α-phase, whereas the unannealed samples retained a photo-inactive δ-phase. The surface chemical composition of the perovskite films was analyzed using angle-resolved XPS, an effective technique for investigating the photochemical and thermal decomposition of perovskite materials. The samples were pre-cleaned using a low-energy ion/cluster beam to prevent damage to the perovskite layers. The survey spectrum of the freshly prepared perovskite/glass samples displayed characteristic peaks, including Pb4f, Br3d, I3d, Cs3d, and C1s. Closer examination between 283 eV and 287 eV identified a peak at approximately 286 eV and a secondary peak at around 284 eV, corresponding to C-N and C-C bonds, respectively. The Pb XPS spectra that were taken 625 hours later of sample preparation and sample treatment show larger Pbo peaks. So, degradation does not stop upon removing the heat and humidity stresses and storing the sample in a nitrogen filled glovebox. We also explored the impact of heat and moisture on the triple halide perovskite. To our knowledge, this is the first report of an XPS study on Cs22Br15.
Description
Keywords
perovskite, angle-resolved XPS analysis
Citation
Mahamudujjaman, Md, Scolfaro, L. M., & Geerts, W. J. (2024). Insights into (Cs0.22FA0.78)Pb(I0.85Br0.15)3 Triple Halide Perovskite films: Stability Investigations via Angle-Resolved XPS Analysis. Poster presented at the Graduate Student Research Conference, San Marcos, Texas.