Synthesis and Electronic Structure of Mid-Infrared Absorbing Cu3SbSe4 and CuxSbSe4 Nanocrystals

Annina Moser; Olesya Yarema; Gregorio Garcia; Mathieu Luisier; Filippo Longo; Emanuel Billeter; Andreas Borgschulte; Maksym Yarema; Vanessa Wood

doi:10.1021/acs.chemmater.3c00911

Synthesis and Electronic Structure of Mid-Infrared Absorbing Cu₃SbSe₄ and Cu_xSbSe₄ Nanocrystals

Chem Mater. 2023 Aug 9;35(16):6323-6331. doi: 10.1021/acs.chemmater.3c00911. eCollection 2023 Aug 22.

Authors

Annina Moser¹, Olesya Yarema¹, Gregorio Garcia², Mathieu Luisier³, Filippo Longo⁴, Emanuel Billeter⁵, Andreas Borgschulte^{4

6}, Maksym Yarema¹, Vanessa Wood¹

Affiliations

¹ Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland.
² Departamento de Tecnología Fotónica y Bioingeniería & Instituto de Energía Solar, ETSI Telecomunicación, Universidad Politécnica de Madrid, Ciudad Universitaria, ES-20840 Madrid, Spain.
³ Institute for Integrated Systems, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland.
⁴ Laboratory for Advanced Analytical Technologies, Empa, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
⁵ Department of Physics, Danmarks Tekniske Universitet, Fysikvej, Building 312, 2800 Kgs. Lyngby, Denmark.
⁶ Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.

Abstract

Aliovalent I-V-VI semiconductor nanocrystals are promising candidates for thermoelectric and optoelectronic applications. Famatinite Cu₃SbSe₄ stands out due to its high absorption coefficient and narrow band gap in the mid-infrared spectral range. This paper combines experiment and theory to investigate the synthesis and electronic structure of colloidal Cu_xSbSe₄ nanocrystals. We achieve predictive composition control of size-uniform Cu_xSbSe₄ (x = 1.9-3.4) nanocrystals. Density functional theory (DFT)-parametrized tight-binding simulations on nanocrystals show that the more the Cu-vacancies, the wider the band gap of Cu_xSbSe₄ nanocrystals, a trend which we also confirm experimentally via FTIR spectroscopy. We show that Sb_Cu antisite defects can create mid-gap states, which may give rise to sub-bandgap absorption. This work provides a detailed study of Cu_xSbSe₄ nanocrystals and highlights the potential opportunities as well as challenges for their application in infrared devices.