Article,
Synthesis and Electronic Structure of Mid-Infrared Absorbing Cu3SbSe4 and Cu x SbSe4 Nanocrystals
Affiliations
- [1] ETH Zurich [NORA names: Switzerland; Europe, Non-EU; OECD];
- [2] Technical University of Madrid [NORA names: Spain; Europe, EU; OECD];
- [3] Swiss Federal Laboratories for Materials Science and Technology [NORA names: Switzerland; Europe, Non-EU; OECD];
- [4] Technical University of Denmark [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD];
- [5] University of Zurich [NORA names: Switzerland; Europe, Non-EU; OECD]
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 CuxSbSe4 nanocrystals. We achieve predictive composition control of size-uniform CuxSbSe4 (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 CuxSbSe4 nanocrystals, a trend which we also confirm experimentally via FTIR spectroscopy. We show that SbCu antisite defects can create mid-gap states, which may give rise to sub-bandgap absorption. This work provides a detailed study of CuxSbSe4 nanocrystals and highlights the potential opportunities as well as challenges for their application in infrared devices.