Mechanical and thermal transport properties of monolayer PbI₂ via first-principles investigations

ABSTRACT

With the synthesis of single-layer lead iodide (PbI₂) in the laboratory in recent years, it has been widely used due to its stable structure and suitable bandgap (2.5 eV). We carried out first-principles calculations and a theoretical analysis to investigate the mechanical properties, electronic structure, and thermal transport properties of monolayer PbI₂. We computed the elastic constant C₁₁ = 14.69 N m⁻¹, layer modulus ${\gamma }_0$ = 9.35 N m⁻¹, and Young’s modulus E^2D = 13.63 N m⁻¹. Our results indicate that monolayer PbI₂ is more flexible than other two-dimensional materials, and it has good ductility. The Poisson’s ratio v of monolayer PbI₂ is 0.27, which means that ionic forces play a major role in the interatomic bonding for PbI₂ layered by van der Waals forces. We also did first-principles calculations for the lattice thermal transport properties of monolayer PbI₂ through the ShengBTE code. The calculated thermal conductivity $k_l$ of monolayer PbI₂ at 300 K is 0.66 W/m K, which agrees well with the experimental data of 0.68 W/m K. Furthermore, its thermal conductivity is much lower than that of other two-dimensional materials. We concluded that the acoustic modes of monolayer PbI₂ make a major contribution to its thermal conductivity.

KEYWORDS:

• Lead iodide (PbI₂)
• Density functional theory (DFT)
• Elastic properties
• Thermal transport

Additional information

Funding

The authors are grateful for the support of the NSAF Joint Fund set up by the National Natural Science Foundation of China and the Chinese Academy of Engineering Physics [grant number U1830101], the Science Challenge Project [grant number TZ2016001], and the National Natural Science Foundation of China [grant number 11504035].