Growth of SnO₂ Nanostructures by Sequential Infiltration Synthesis in Block Copolymer using Atomic Layer Deposition

Templating inorganic materials nanostructures through a combination of block copolymer (BCP) self-assembly and sequential infiltration synthesis (SIS) is been gaining significant attention for applications in coatings, energy storage, advance patterning, etc. Up until now, materials such as Al₂O₃, ZnO, TiO₂ etc., have been successfully grown using SIS technique. However, there are several important functional materials yet to be synthesized and nanostructured through SIS technique. Among them, Tin oxide (SnO₂) is a transparent conductive oxide (TCO) which possesses interesting thermal and gas sensing properties and is commonly used in electrodes for solar cells and light emitting diode.

Here, we report the growth of SnO₂ by SIS within polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) polymer with and without alumina seeding layer using Tetrakis(dimethylamino)Tin and H₂O₂ as tin and oxygen precursors, respectively. Subsequent removal of the polymer results in highly ordered and porous SnO₂ nanostructure as evident by scanning and transmission electron microscopy (SEM and TEM, respectively). Growth of Tin oxide has been confirmed by elemental analysis using scanning TEM energy dispersive X-ray (EDS) characterization. Furthermore, in-situ mass growth characterization together with structural and chemical analysis shed light on the various growth mechanisms observed when the growth is carried out with and without alumina SIS pretreatment and as a function of polymer chemistry. This research shows, for the first time, the utilization of large metalorganic precursor and hydrogen peroxide in SIS and opens pathways for fabrication for new SIS chemistries.