Core Levels, Band Alignments, and Valence-Band States in CuSbS<sub>2</sub> for Solar Cell Applications

Whittles, Thomas J ORCID: 0000-0002-5154-7511, Veal, Tim D ORCID: 0000-0002-0610-5626, Savory, Christopher N, Welch, Adam W, Lucas, Francisco Willian de Souza, Gibbon, James T ORCID: 0000-0003-1548-0791, Birkett, Max ORCID: 0000-0002-6076-6820, Potter, Richard J ORCID: 0000-0003-0896-4536, Scanlon, David O, Zakutayev, Andriy
et al (show 1 more authors) (2017) Core Levels, Band Alignments, and Valence-Band States in CuSbS<sub>2</sub> for Solar Cell Applications. ACS APPLIED MATERIALS & INTERFACES, 9 (48). pp. 41916-41926.

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The earth-abundant material CuSbS<sub>2</sub> (CAS) has shown good optical properties as a photovoltaic solar absorber material, but has seen relatively poor solar cell performance. To investigate the reason for this anomaly, the core levels of the constituent elements, surface contaminants, ionization potential, and valence-band spectra are studied by X-ray photoemission spectroscopy. The ionization potential and electron affinity for this material (4.98 and 3.43 eV) are lower than those for other common absorbers, including CuIn<sub>x</sub>Ga<sub>(1-x)</sub>Se<sub>2</sub> (CIGS). Experimentally corroborated density functional theory (DFT) calculations show that the valence band maximum is raised by the lone pair electrons from the antimony cations contributing additional states when compared with indium or gallium cations in CIGS. The resulting conduction band misalignment with CdS is a reason for the poor performance of cells incorporating a CAS/CdS heterojunction, supporting the idea that using a cell design analogous to CIGS is unhelpful. These findings underline the critical importance of considering the electronic structure when selecting cell architectures that optimize open-circuit voltages and cell efficiencies.

Item Type: Article
Uncontrolled Keywords: CuSbS2, copper antimony sulfide, XPS, DFT, thin-film solar cells, band alignments, density of states
Depositing User: Symplectic Admin
Date Deposited: 28 Feb 2018 16:16
Last Modified: 30 Jan 2024 10:40
DOI: 10.1021/acsami.7b14208
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