Tin Halide Perovskite Nanostructures

Novel functional nanomaterials are crucial in advancing technology and fostering innovation across multiple sectors— from healthcare and energy to environmental protection and electronics. A semiconductor nanocrystal is one such functional nanomaterial, exhibiting optical and electronic properties that depend on its size. Notably, nanocrystals of a recently revived semiconductor, metal halide perovskite, show great potential for next-generation optoelectronic devices.
Tin halide perovskites, being heavy metal free, are deemed as more sustainable alternative to lead halide perovskites. However, they are less explored due to their instability in ambient atmosphere and inferior optical properties. In this thesis, I investigated the colloidal nanochemistry of tin halide perovskites and establish their structure-property relationships. I have successfully synthesized monodisperse, colloidally stable tin halide perovskite nanocrystals using sub-stoichiometric ratio of ligands and an excess of tin halide salt. Owing to their ionic nature, tin halide perovskites exhibit dimensional dynamics related to intercalated cation and undergo facile ion exchange reactions. It is discovered that tin bromide is more prone to forming higher-dimensional structures compared to lead bromide.
To prevent the formation of low dimensional structures, an amine free synthesis was developed to form formamidinium tin iodide nanocrystals. Furthermore, with hybrid organic-inorganic encapsulation, the ambient stability of tin halide perovskite nanocrystals was enhanced from an hour to a record 15 days, to help facilitate their photophysical studies. This research work highlights the insistent necessity for a comprehensive understanding of the synthesis and photophysical properties of tin-halide perovskite nanostructures to unlock their full potential.