Earth-Abundant Chalcogenide Photovoltaic Devices with over 5% Efficiency Based on a Cu2 BaSn(S,Se)4 Absorber.


Journal Article

In recent years, Cu2 ZnSn(S,Se)4 (CZTSSe) materials have enabled important progress in associated thin-film photovoltaic (PV) technology, while avoiding scarce and/or toxic metals; however, cationic disorder and associated band tailing fundamentally limit device performance. Cu2 BaSnS4 (CBTS) has recently been proposed as a prospective alternative large bandgap (~2 eV), environmentally friendly PV material, with ~2% power conversion efficiency (PCE) already demonstrated in corresponding devices. In this study, a two-step process (i.e., precursor sputter deposition followed by successive sulfurization/selenization) yields high-quality nominally pinhole-free films with large (>1 µm) grains of selenium-incorporated (x = 3) Cu2 BaSnS4-x Sex (CBTSSe) for high-efficiency PV devices. By incorporating Se in the sulfide film, absorber layers with 1.55 eV bandgap, ideal for single-junction PV, have been achieved within the CBTSSe trigonal structural family. The abrupt transition in quantum efficiency data for wavelengths above the absorption edge, coupled with a strong sharp photoluminescence feature, confirms the relative absence of band tailing in CBTSSe compared to CZTSSe. For the first time, by combining bandgap tuning with an air-annealing step, a CBTSSe-based PV device with 5.2% PCE (total area 0.425 cm2 ) is reported, >2.5× better than the previous champion pure sulfide device. These results suggest substantial promise for the emerging Se-rich Cu2 BaSnS4-x Sex family for high-efficiency and earth-abundant PV.

Full Text

Duke Authors

Cited Authors

  • Shin, D; Zhu, T; Huang, X; Gunawan, O; Blum, V; Mitzi, DB

Published Date

  • June 2017

Published In

Volume / Issue

  • 29 / 24

PubMed ID

  • 28425630

Pubmed Central ID

  • 28425630

Electronic International Standard Serial Number (EISSN)

  • 1521-4095

International Standard Serial Number (ISSN)

  • 0935-9648

Digital Object Identifier (DOI)

  • 10.1002/adma.201606945


  • eng