**5. Conclusion**

**57** 2D PtSe2 is an excellent material, its unique layer dependent properties. The fact that it is stable under ambient conditions unlike most other TMDCs makes it a great choice for scientific study. This book chapter gives an overview of the layer dependent properties of PtSe2 like band gap, density of states and thermal conductivity. DFT was employed to study the electronic band structure of 1L, 2L, 3L and bulk PtSe2, which showed that there is a drastic reduction of band gap when moving from monolayer to bilayer.

Optothermal method by using Raman spectroscopy was employed to explore the thermal conductivity of PtSe2 flakes. The Raman study was carried out by both varying the power and temperature of the sample. The incident laser power was varied from 0.25 to 2.27 mW and the temperature of the sample was varied from 107 to 353 K, the power coefficient (p) and the temperature coefficient (1) was calculated from these data. The thermal conductivity was obtained by using both coefficients for a specific thickness of the flake. The optothermal study reveals that the saturation thermal conductivity of PtSe2 with thickness more than 40 nm is about 39–41 W/ mK. Perpendicular and parallel polarization study was done for 59 nm thick flake, which reveals that both the in plane and out of plane modes didn't suffer any change in intensity in contrast with thinner flake (5 nm thick). The authors hope this book chapter shall aid the exploration endeavour regarding PtSe2.
