Elucidating Structural Disorder and the Effects of Cu Vacancies on the Electronic Properties of Cu2ZnSnS4

Kuang Yu, Emily A. Carter

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Although a promising photovoltaic material that is inexpensive and easy to manufacture, Cu2ZnSnS4 (CZTS) suffers from a low open circuit voltage thought to be due to local potential fluctuations caused by a disordered Cu/Zn sublattice. The disordered character of CZTS is difficult to study experimentally and has been universally neglected in computational studies. Here, we develop a cluster expansion model that enables simulation of the order-disorder phase transition in CZTS for the first time. With a proper atomic structure of the disordered phase in hand, we investigate the temperature-dependent voltage loss in CZTS, illustrating intrinsic limitations of existing synthesis methods and suggesting an optimal annealing temperature. We offer one explanation why Cu-poor CZTS is optimally efficient, as Cu vacancies increase the band gap via interactions between free carriers and the disordered nature of as-grown CZTS. Accordingly, increasing carrier concentrations may be an effective strategy to flatten the fluctuating potentials.

Original languageEnglish (US)
Pages (from-to)864-869
Number of pages6
JournalChemistry of Materials
Volume28
Issue number3
DOIs
StatePublished - Feb 9 2016

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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