Investigation of thermoelectric properties of cadmium selenide CdnSen (n= 7, 11, 13) molecular junctions: a DFT study

Hussein Hakim Abed; Mohsin K Al-Khaykanee; Hayder M Abduljalil; Mudar Ahmed Abdulsattar

doi:10.1007/s00894-023-05805-z

Investigation of thermoelectric properties of cadmium selenide Cd_nSe_n (n= 7, 11, 13) molecular junctions: a DFT study

J Mol Model. 2023 Dec 16;30(1):12. doi: 10.1007/s00894-023-05805-z.

Authors

Hussein Hakim Abed¹, Mohsin K Al-Khaykanee², Hayder M Abduljalil³, Mudar Ahmed Abdulsattar⁴

Affiliations

¹ Department of Physics, College of Science, University of Babylon, Hilla, Iraq. hakimhussein.2017@gmail.com.
² Department of Physics, College of Science, University of Babylon, Hilla, Iraq. mohsin.kad@gmail.com.
³ Department of Physics, College of Science, University of Babylon, Hilla, Iraq.
⁴ Ministry of Science and Technology, Baghdad, Iraq.

PMID: 38102331
DOI: 10.1007/s00894-023-05805-z

Abstract

Context: The thermoelectric properties of cadmium selenide (Cd_nSe_n) molecular junctions (n = 7, 11, 13) were investigated before and after adding hydrogen atoms. The effects of hydrogen passivation on the transmission and thermopower curves were analyzed. CdSe-diamantane (Cd₇Se₇) and CdSe-tetramantane (Cd₁₁Se₁₁) junctions exhibited the best thermoelectric performance due to their low surface reconstruction energy, which is attributed to the number of dangling and unsaturated bonds. This study guides the design of new molecular junctions with desired thermoelectric properties.

Method: The electrical and thermal properties of cadmium selenide (Cd_nSe_n) molecular junctions (n = 7, 11, 13) were investigated using a ballistic quantum transport method based on the non-equilibrium Green's function (NEGF) approach. Thermoelectric properties were calculated for the molecular junctions with different structures before and after hydrogen passivation. Density functional theory (DFT) calculations were performed at the B3LYP level with the 3-21G basis set for the Cd atoms and the 6-31G** basis set for the Se atoms. The SIESTA and GOLLUM codes were used to study the effect of changing the shape and size of each structure on its electrical and thermal characteristics.

Keywords: Cadmium selenide; DFT; Molecular junctions; Thermoelectric properties.