First-principles investigation of the role of Cr in the electronic properties of the two-dimensional MoxCr1xSe2 and WxCr1xSe2 alloys

A. C. Dias, Helena Bragança, Matheus P. Lima, and Juarez L. F. Da Silva
Phys. Rev. Materials 6, 054001 – Published 12 May 2022
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Abstract

The tuning of the structural and electronic properties of two-dimensional semiconductor monolayers is highly desirable for designing van der Waals heterostructures, which can be employed for several optoelectronic applications. Here, we report a theoretical investigation based on the combination of spin-polarized density functional theory calculations and alloying structures generated by the special quasirandom structure method to investigate the energetic stability and band gap engineering of the compounds MoxCr1xSe2 and WxCr1xSe2 as a function of the Cr composition for x=0 up to 1. We found that even a small concentration of Cr already flattens the low-energy electronic bands and decreases the fundamental electronic band gap. Due the lattice mismatch of the compounds CrSe2 and Mo(W)Se2, the renormalization of the electronic properties is nonlinear as a function of the Cr composition. We found bowing parameters for the work function and band gap that change in magnitude from 0.066 to 1.178eV, respectively. From our analyses, Cr alloying decreases the band gap of these monolayers in the direction of the maximum performance band gap predicted by the Shockley-Queisser limit for photovoltaic applications. Band alignment analysis reveals that stacks of Mo(W)xCr1xSe2 monolayers with particular compositions x can form type II heterojunctions with a high solar harvesting efficiency.

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  • Received 11 December 2021
  • Revised 2 April 2022
  • Accepted 22 April 2022

DOI:https://doi.org/10.1103/PhysRevMaterials.6.054001

©2022 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

A. C. Dias1,*, Helena Bragança2,†, Matheus P. Lima3,‡, and Juarez L. F. Da Silva1,§

  • 1São Carlos Institute of Chemistry, University of São Paulo, P.O. Box 780, 13560-970 São Carlos, São Paulo, Brazil
  • 2Physical Institute and International Center for Physics, Universidade de Brasília, Brasília 70919-970, Distrito Federal, Brazil
  • 3Department of Physics, Federal University of São Carlos, 13565-905 São Carlos, São Paulo, Brazil

  • *alexandre.dias@unb.br
  • helena.braganca@unb.br
  • mplima@df.ufscar.br
  • §juarez_dasilva@iqsc.usp.br

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Issue

Vol. 6, Iss. 5 — May 2022

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