Ligand-Controlled Colloidal Synthesis and Electronic Structure Characterization of Cubic Iron Pyrite (FeS2) Nanocrystals

• Published in: Chemistry of materials Vol. 25; no. 9; pp. 1615 - 1620
• Main Authors: Lucas, J. Matthew, Tuan, Chia-Chi, Lounis, Sebastien D, Britt, David K, Qiao, Ruimin, Yang, Wanli, Lanzara, Alessandra, Alivisatos, A. Paul
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14.05.2013
• Subjects: nanocrystal; iron pyrite; resonant inelastic X-ray spectroscopy; X-ray absorption; photovoltaics; FeS2
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm304152b

Iron pyrite (FeS2) is a promising photovoltaic absorber because of its Earth abundance, high optical extinction, and infrared band gap (E g = 0.95 eV), but its use has been hindered because of the difficulty of phase pure synthesis. Pyrite phase purity is a paramount concern, as other phases of iron sulfide have undesirable electronic properties. Here we report the synthesis of phase pure iron pyrite nanocrystals with cubic morphology and a mean dimension of 80 nm. Control over the nanocrystal shape was achieved using an unusual ligand, 1-hexadecanesulfonate. The particles were characterized via synchrotron X-ray spectroscopy, indicating an indirect band gap of 1.00 ± 0.11 eV and a valence bandwidth of nearly 1 eV. Transmission electron microscopy from early reaction stages suggests a nucleation and growth mechanism similar to solution precipitation syntheses typical of metal oxide nanocrystals, rather than the diffusion-limited growth process typical of hot-injection metal chalcogenide nanocrystal syntheses.