First-principles study of the band structure and optical absorption of CuGaS2

Irene Aguilera, Julien Vidal, Perla Wahnón, Lucia Reining, and Silvana Botti
Phys. Rev. B 84, 085145 – Published 30 August 2011

Abstract

CuGaS2 is the most promising chalcopyrite host for intermediate-band thin-film solar cells. Standard Kohn-Sham density functional theory fails in describing the band structure of chalcopyrite materials, due to the strong underestimation of the band gap and the poor description of p-d hybridization, which makes it inadvisable to use this approach to study the states in the gap induced by doping. We used a state-of-the-art restricted self-consistent GW approach to determine the electronic states of CuGaS2: in the energy range of interest for optical absorption, the GW corrections shift the Kohn-Sham bands almost rigidly, as we proved through analysis of the effective masses, bandwidths, and relative position of the conduction energy valleys. Furthermore, starting from the GW quasiparticle bands, we calculated optical absorption spectra using different approximations. We show that the time-dependent density functional theory can be an efficient alternative to the solution of the Bethe-Salpeter equation when the exchange-correlation kernels derived from the Bethe-Salpeter equation are employed. This conclusion is important for further studies of optical properties of supercells including dopants.

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  • Received 13 January 2011

DOI:https://doi.org/10.1103/PhysRevB.84.085145

©2011 American Physical Society

Authors & Affiliations

Irene Aguilera1,2,3, Julien Vidal2,3,4, Perla Wahnón1, Lucia Reining2,3, and Silvana Botti2,3,5,*

  • 1Instituto de Energía Solar and Departamento de Tecnologías Especiales, ETSI Telecomunicación, UPM, Ciudad Universitaria, ES-28040 Madrid, Spain
  • 2Laboratoire des Solides Irradiés (LSI), École Polytechnique, CNRS, CEA-DSM, F-91128 Palaiseau, France
  • 3European Theoretical Spectroscopy Facility (ETSF)
  • 4Institute for Research and Development of Photovoltaic Energy (IRDEP), UMR 7174 CNRS/EDF/ENSCP, 6 Quai Watier, F-78401 Chatou, France
  • 5Laboratoire de Physique de la Matière Condensée et Nanostructures (LPMCN), Université “Claude Bernard” Lyon 1, CNRS, Domaine Scientifique de la Doua, F-69622 Villeurbanne, France

  • *silvana.botti@polytechnique.edu

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Issue

Vol. 84, Iss. 8 — 15 August 2011

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