Carolin Sutter-Fella1,Mriganka Singh1,Maged Abdelsamie1,Tim Kodalle1
Lawrence Berkeley National Laboratory1
Carolin Sutter-Fella1,Mriganka Singh1,Maged Abdelsamie1,Tim Kodalle1
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 instabilities, as well as moisture sensitivity. Triple cation, mixed halide perovskite compositions have been reported to be more thermally stable, exhibit less 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 solvent-antisolvent interaction and evaluate if the antisolvent induces oversaturation accompanied by solvate phase formation or if it removes the solvent and thereby suppresses solvate phases. 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 solvate and perovskite phase evolution and its mutual correlation with the solvent and antisolvent to allow for better synthetic control.