Tin(II) selenide is a narrow band-gap (IV-VI) semiconductor structurally analogous to black phosphorus.

[6] Sheet-like nanocrystalline SnSe with an orthorhombic phase has been prepared with good purity and crystallization via a reaction between a selenium alkaline aqueous solution and tin(II) complex at room temperature under atmospheric pressure.

Its high efficiency is most likely due to low thermal conductivity of the crystal, the electronic structure may have as important role: SnSe has highly anisotropic valence band structure, which consists of multiple valleys that act as independent channels for very mobile, low effective-mass charge transport within, and heavy-carrier conductivity perpendicular to the layers.

The dynamic structural behavior of SnSe involving the reversible phase transition helps to preserve the high power factor.

The poor ability to carry heat through its lattice enables the resulting record high thermoelectric conversion efficiency.

[19] The previously reported nanostructured all-scale hierarchical PbTe-4SrTe-2Na (with a ZT of 2.2) exhibits a lattice thermal conductivity of 0.5 W m−1 K−1.

The unprecedentedly high ZT ~2.6 of SnSe arises primarily from an even lower lattice thermal conductivity of 0.23 W m−1 K−1.

[20] However, in order to take advantage of this ultralow lattice thermal conductivity, the synthesis method must result in macroscale single crystals as p-type polycrystalline SnSe has been shown to have a significantly reduced ZT.

[6] Tin(II) selenide has potential as a solid-state lubricant, due to the nature of its interlayer bonding.