Structural Dynamics and Tunability for Colloidal Tin Halide Perovskite Nanostructures.

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Chemistry

Background:

• Lead halide perovskites are promising for optoelectronics due to tunability.
• Replacing lead with tin is desired for sustainability but hindered by Sn2+ instability and synthesis challenges.

Purpose of the Study:

• To develop an optimized synthetic route for stable, tunable, and monodisperse tin-based perovskite nanocrystals.
• To understand the chemical processes governing the synthesis of CsSnI3 nanocrystals.

Main Methods:

• Synthesis of CsSnI3 nanocrystals using SnI2, oleylamine, oleic acid, and Cs-oleate precursors.
• Optimization of precursor ratios (excess SnI2, substoichiometric Sn:ligand) and reaction conditions.
• Characterization using structural, compositional, and optical analyses.
• First-principle density functional theory calculations.

Main Results:

• Achieved stable, tunable, and monodisperse CsSnI3 nanocrystals (10 nm) in the γ-orthorhombic phase.
• Identified excess SnI2 and substoichiometric Sn:ligand ratios as key for stability.
• Demonstrated nucleation and growth via (R-NH3+)2SnI4 nanosheets, leading to 3D CsSnI3 and 2D Ruddlesden-Popper phases.

Conclusions:

• An optimized synthesis yields stable tin halide perovskite nanocrystals.
• Understanding the formation pathway of intermediate nanosheets is crucial for controlling crystal structure and stability.
• This work enables the exploitation of tin halide perovskites for optoelectronic applications.