Crystallization Dynamics of Hybrid Perovskite Mediated by a Biopolymer: From Precursor Solution to Thin Film

Abstract The fascinating optoelectronic properties of Metal Halide Perovskites (MHPs) have renewed interest in the development of innovative photovoltaic devices. Controlling the MHP crystallization process is crucial for achieving high‐performing solar cells especially when scaling up deposition technologies. To this aim, this work leverages a practical toolkit of characterization techniques to model the crystallization kinetics of MHPs and additives. The crystallization kinetics of MHPs from solution mediated by the starch is taken as a reference, with a glance at scalable printing techniques. The study of the equilibrium of chemical species in solution shows that starch influences the balance of ionic species, stabilizing the lead(II)iodide‐methylammonium iodide‐dimethylsulfoxide(PbI 2 ·MAI·DMSO) adduct and causing dissociation of MAI aggregates. A combination of Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) analyses, using the Kissinger model, reveals a heterogeneous crystallization mechanism with delayed crystallization mediated by the starch, leading to the formation of the characteristic Liesegang ring grains. Upscaling deposition via blade coating further demonstrates that starch mitigates intrinsic stress during deposition in open air, resulting in a smoother, more homogeneous perovskite film with minimal gaps. This approach highlights the crucial role of starch in MHPs crystallization, providing insights into the dynamics that influence MHP properties and performance, while enabling further scalable deposition techniques.