Tailoring SnO₂ Defect States and Structure: Reviewing Bottom-Up Approaches to Control Size, Morphology, Electronic...

Tin oxide (SnO₂) is a versatile n-type semiconductor with a wide bandgap of 3.6 eV that varies as a function of its polymorph, i.e., rutile, cubic or orthorhombic. In this review, we survey the crystal and electronic structures, bandgap and defect states of SnO₂. Subsequently, the significance of the defect states on the optical properties of SnO₂ is overviewed. Furthermore, we examine the influence of growth methods on the morphology and phase stabilization of SnO₂ for both thin-film deposition and nanoparticle synthesis. In general, thin-film growth techniques allow the stabilization of high-pressure SnO₂ phases via substrate-induced strain or doping. On the other hand, sol-gel synthesis allows precipitating rutile-SnO₂ nanostructures with high specific surfaces. These nanostructures display interesting electrochemical properties that are systematically examined in terms of their applicability to Li-ion battery anodes. Finally, the outlook provides the perspectives of SnO₂ as a candidate material for Li-ion batteries, while addressing its sustainability.