20th Brazilian Workshop On Semiconductor Physics

Pd-based dichalcogenides: the 1T and the novel 1OT regular and Janus structures: from electronic to thermal properties

Non programmé

20m

Instituto Tecnológico de Aeronáutica

Oral

Orateur

Prof. Elie A. Moujaess (Physics department - Federal University of Rôndonia)

Description

Abstract

The discovery of two dimensional (2D) graphene has opened the doors to investigate a myriad of new 2D materials that have better characteristics. Out of these are the transition metal dichalcogenides (TMDs). In this talk, I will shine light on the electronic, optical and thermal properties of the 1T [1] Pd-based dichalcogenides, namely PdS2, PdSe2, PdSSe, PdSTe, and PdSeTe systems, that do not have a fair share of research like the Mo or W-based TMDs. Our results show that the thermal electronic conductivity (e), the electronic conductivity (σe), the Seebeck effect (S), and the figure of merit (ZT) along the x and y directions register the largest values in the case of electron doping for the PdSe2 and PdSeTe 2D crystals [1]. Additionally, ZT of the Janus structures are larger than their corresponding pristine PdX2 (X = S, Se) structures [1]. Once synthesized, such information is crucial for the implementation of the PdXY (Y = Se, Te) structures in industrial applications.

I will also discuss the electronic and optical properties for the novel 1OT [2] metastable (with monoclinic symmetry) structures that we have modelled in our group. Our calculations reveal that, without the inclusion of spin-orbit coupling, all structures considered have a semi-metallic behavior with a non-zero (DOS) at the Fermi level. Furthermore, they demonstrate a wider range of absorption spectra than 1T systems, and can emit or absorb within the infrared (IR) regime. They are dynamically stable and their thermal lattice conductivities should be lower than their 1T analogs, making them suitable candidates for thermoelectric devices. The Born-Oppenheimer Molecular Dynamics (MD) simulations [3] show that the 1OT PdS2 and PdSe2 structures are thermally stable at temperatures above 300 K, while the Janus PdSSe system remains stable up to temperatures close to 600 K and is completely destroyed at 900K [2].

References

[1] Elie. A. Moujaes and W. A. Diery, J. Phys. Condens. Matter. 31, 455502 (2019).

[2] Elie A. Moujaes and W. A. Diery, Physica E Low Dimens. Syst. Nanostruct 128, 114611 (2021).

[3] M. Born and J. R. Oppenheimer, Annalen der Physik. 389 457–484 (1927).