Tim Kodalle1,Mriganka Singh1,Maged Abdelsamie1,Carolin Sutter-Fella1
Lawrence Berkeley National Laboratory1
Tim Kodalle1,Mriganka Singh1,Maged Abdelsamie1,Carolin Sutter-Fella1
Lawrence Berkeley National Laboratory1
Halide perovskites with mixed A- and X-site cations and anions, respectively, are important to overcome challenges such as thermal and structural instability, and moisture sensitivity in single cation MA/FA/CsPbX<sub>3</sub>. Triple cation, mixed halide perovskite compositions have been reported to be more thermally stable, exhibit fewer phase impurities, and are less affected by the processing conditions than single cation perovskites. In this work, we present a multimodal in situ study on the formation of Cs<sub>0.05</sub>FA<sub>0.81</sub>MA<sub>0.14</sub>Pb(I<sub>0.85</sub>Br<sub>0.15</sub>)<sub>3</sub> by combining structural information from grazing-incidence wide-angle synchrotron X-ray scattering (GIWAXS) and optical properties from photoluminescence (PL) spectroscopy. This study covers the predominantly used solvents and solvent systems DMF, DMSO, and mixtures thereof. We are looking at the effect of the solvent used and the application of antisolvent dropping. We find that the non-perovskite delta-FAPbI<sub>3</sub> appears in all crystallization pathways. It is strongly correlated with the antisolvent dripping and temporally close to the perovskite phase formation. It was also found that the delta phase is more stable in DMF than in DMSO systems. These findings provide novel insights into perovskite phase evolution and its correlation with the solvent and antisolvent to allow for better synthetic control.