2021/07/01 by Bryce A. Tappan, Bonan Zhu, Patrick Cottingham +3 · 36 citations
Materials Science · Engineering · Chemistry · #Quantum Dots Synthesis And Properties #Chalcogenide Semiconductor Thin Films #Copper-based nanomaterials and applications #Metastability #Tetragonal crystal system #Crystallography #Nanocrystal #Density functional theory #Crystal structure #Materials science #Band gap #Polymorphism (computer science) #Chemical physics #Chemistry #Nanotechnology #Computational chemistry #Optoelectronics
paper · open access · doi:10.1021/acs.nanolett.1c02045
published in Nano Letters 21(13), 5881-5887 (American Chemical Society)
openalex publication_date 2021/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Structural polymorphism is known for many bulk materials; however, on the nanoscale metastable polymorphs tend to form more readily than in the bulk, and with more structural variety. One such metastable polymorph observed for colloidal Ag 2 Se nanocrystals has traditionally been referred to as the “tetragonal” phase. While there are reports on the chemistry and properties of this metastable polymorph, its crystal structure, and therefore electronic structure, has yet to be determined. We report that an anti-PbCl 2 -like structure type (space group P 2 1 / n ) more accurately describes the powder X-ray diffraction and X-ray total scattering patterns of colloidal Ag 2 Se nanocrystals prepared by several different methods. Density functional theory (DFT) calculations indicate that this anti-PbCl 2 -like Ag 2 Se polymorph is a dynamically stable, narrow-band-gap semiconductor. The anti-PbCl 2 -like structure of Ag 2 Se is a low-lying metastable polymorph at 5–25 meV/atom above the ground state, depending on the exchange-correlation functional used.