Low-Temperature Atomic Layer Deposition of CuSbS2 for Thin-Film Photovoltaics

Shannon C Riha; Alexandra A Koegel; Jonathan D Emery; Michael J Pellin; Alex B F Martinson

doi:10.1021/acsami.6b13033

Low-Temperature Atomic Layer Deposition of CuSbS₂ for Thin-Film Photovoltaics

ACS Appl Mater Interfaces. 2017 Feb 8;9(5):4667-4673. doi: 10.1021/acsami.6b13033. Epub 2017 Jan 24.

Authors

Shannon C Riha¹, Alexandra A Koegel¹, Jonathan D Emery^{2

3}, Michael J Pellin^{4

3}, Alex B F Martinson^{4

3}

Affiliations

¹ Department of Chemistry, University of Wisconsin-Stevens Point , Stevens Point, Wisconsin 54481, United States.
² Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States.
³ Argonne-Northwestern Solar Energy Research (ANSER) Center, Argonne National Laboratory , Argonne, Illinois 60439, United States.
⁴ Materials Science Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.

PMID: 28117960
DOI: 10.1021/acsami.6b13033

Abstract

Copper antimony sulfide (CuSbS₂) has been gaining traction as an earth-abundant absorber for thin-film photovoltaics given its near ideal band gap for solar energy conversion (∼1.5 eV), large absorption coefficient (>10⁴ cm^-1), and elemental abundance. Through careful in situ analysis of the deposition conditions, a low-temperature route to CuSbS₂ thin films via atomic layer deposition has been developed. After a short (15 min) postprocess anneal at 225 °C, the ALD-grown CuSbS₂ films were crystalline with micron-sized grains, exhibited a band gap of 1.6 eV and an absorption coefficient >10⁴ cm^-1, as well as a hole concentration of 10¹⁵ cm^-3. Finally, the ALD-grown CuSbS₂ films were paired with ALD-grown TiO₂ to form a photovoltaic device. This photovoltaic device architecture represents one of a very limited number of Cd-free CuSbS₂ PV device stacks reported to date, and it is the first to demonstrate an open-circuit voltage on par with CuSbS₂/CdS heterojunction PV devices. While far from optimized, this work demonstrates the potential for ALD-grown CuSbS₂ thin films in environmentally benign photovoltaics.

Keywords: CuSbS2; atomic layer deposition; copper antimony sulfide; photovoltaics; ternary metal sulfide; thin film; thin-film solar cell.