In the bulk form （TlSe）, Thalium selenide, has band-gap at around 0.7 eV and display strong photoluminescence.

In the bulk form (TlSe), Thalium selenide, has band-gap at around 0.7 eV and display strong photoluminescence. Similar to molybdenum disulfide, it has layered structure (lamellar) with weak interlayer coupling, enabling to isolate down to monolayers. Each monolayer is four atoms thick (Se-Tl-Tl-Se) that is roughly 0.9-1.0 nm. In the literature, monolayer TlSe is currently under-studied, yet to be discovered. Raman peaks are sharp and strong indicating high crystallinity.   Our crystals are grown by state-of-the-art growth techniques after 8 weeks and show high crystallinity. The size of the samples is typically around ~4mm in size. TlSe has a layered structure with weak interlayer coupling. Single crystal TlSe comes ready for exfoliation and is ideal for 2D research.