High-temperature decomposition of Cu2BaSnS4with Sn loss reveals newly identified compound Cu2Ba3Sn2S8

Journal Article (Journal Article)

The earth-abundant quaternary compound Cu BaSnS is being currently studied as a candidate for photovoltaics and as a photocathode for water splitting. However, the chemical stability of this phase during synthesis is unclear. The synthesis of other quaternary tin-sulphur-based absorbers (e.g., Cu ZnSnS ) involves an annealing step at high temperature under sulphur gas atmosphere, which can lead to decomposition into secondary phases involving Sn loss from the sample. As the presence of secondary phases can be detrimental for device performance, it is crucial to identify secondary phase chemical, structural and optoelectronic properties. Here we used a combination ofin situEDXRD/XRF and TEM to identify a decomposition pathway for Cu BaSnS . Our study reveals that, while Cu BaSnS remains stable at high sulphur partial pressure, the material decomposes at high temperatures into Cu BaS and the hitherto unknown compound Cu Ba Sn S if the synthesis is performed under low partial pressure of sulphur. The presence of Cu BaS in devices could be harmful due to its high conductivity and relatively lower band gap compared to Cu BaSnS . The analysis of powder diffraction data reveals that the newly identified compound Cu Ba Sn S crystallizes in the cubic system (space groupI4̄3d) with a lattice parameter ofa= 14.53(1) Å. A yellow powder of Cu Ba Sn S has been synthesized, exhibiting an absorption onset at 2.19 eV. 2 4 2 4 2 4 2 4 4 3 2 3 2 8 4 3 2 4 2 3 2 8 2 3 2 8

Full Text

Duke Authors

Cited Authors

  • Márquez, JA; Sun, JP; Stange, H; Ali, H; Choubrac, L; Schäfer, S; Hages, CJ; Leifer, K; Unold, T; Mitzi, DB; Mainz, R

Published Date

  • June 14, 2020

Published In

Volume / Issue

  • 8 / 22

Start / End Page

  • 11346 - 11353

Electronic International Standard Serial Number (EISSN)

  • 2050-7496

International Standard Serial Number (ISSN)

  • 2050-7488

Digital Object Identifier (DOI)

  • 10.1039/d0ta02348e

Citation Source

  • Scopus