Small-angle neutron scattering

Chemistry

Thin film

Scattering

Materials science

Recrystallization (geology)

Oleylamine

Spin coating

Engineering

Chemical physics

Physics

Nanocrystal

Crystallography

Metastability

Neutron scattering

Nanotechnology

Organic chemistry

Crystallization

Nucleation

Biology

Optics

Supersaturation

Orthorhombic crystal system

Crystal structure

Grazing-incidence small-angle scattering

Chemical engineering

Dissolution

Nanocrystalline material

Paleontology

Nature Communications

Complex phenomena are prevalent during the formation of materials, which affect their processing-structure-function relationships. Thin films of methylammonium lead iodide (CH3NH3PbI3, MAPI) are processed by spin coating, antisolvent drop, and annealing of colloidal precursors. The structure and properties of transient and stable phases formed during the process are reported, and the mechanistic insights of the underlying transitions are revealed by combining in situ data from grazing-incidence wide-angle X-ray scattering and photoluminescence spectroscopy. Here, we report the detailed insights on the embryonic stages of organic-inorganic perovskite formation. The physicochemical evolution during the conversion proceeds in four steps: i) An instant nucleation of polydisperse MAPI nanocrystals on antisolvent drop, ii) the instantaneous partial conversion of metastable nanocrystals into orthorhombic solvent-complex by cluster coalescence, iii) the thermal decomposition (dissolution) of the stable solvent-complex into plumboiodide fragments upon evaporation of solvent from the complex and iv) the formation (recrystallization) of cubic MAPI crystals in thin film.

Out-of-equilibrium processes in crystallization of organic-inorganic perovskites during spin coating