Wide Range Optical Stability Study of Ionic Based Hybrid Perovskites for Solar Cells

Organic/Inorganic halide perovskites are significant for their potential in the commercialization of solar cells due to their low cost and high efficiency. We study the stability of two FA0.78Cs0.22Pb(I0.85Br0.15)3 thin films: (1) A 1 m DMF based ink with FAAc additive for nucleation and growth without anti-solvent step or gas quenching; (2) A 1 m DMF/DMSO based ink with 3 mol% of MAPbCl additive optimized for nucleation and growth with gas quenching.

We focused on the stability of films spin-casted and slot-die printed from both inks on glass substrates. The effects of external degradation of moisture, light, and atmosphere were studied. The halide perovskite stability was studied by measurement of the optical properties using FTIR, UV-Vis, and variable angle ellipsometry. Stability of annealed/unannealed samples were tested in atmosphere concurrently from 450nm to 2500nm.

UV-Vis shows stable bandgaps on annealed samples with less than 10 meV variation over 12 hours. The presence of FA and MA ionic signatures were able to be tracked via FTIR analysis.