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Title: Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides

Abstract

Two-dimensional (2D) nanocrystals of CdX (X = S, Se, Te) typically grown by colloidal synthesis are coated with organic ligands. Recent experimental work on ZnSe showed that the organic ligands can be removed at elevated temperature, giving a freestanding 2D sheet of ZnSe. In this theoretical work, freestanding single- to few-layer sheets of CdX, each possessing a pseudo honeycomb lattice, are considered by cutting along all possible lattice planes of the bulk zinc blende (ZB) and wurtzite (WZ) phases. Using density functional theory, we have systematically studied their geometric structures, energetics, and electronic properties. A strong surface distortion is found to occur for all of the layered sheets, and yet all of the pseudo honeycomb lattices are preserved, giving unique types of surface corrugations and different electronic properties. The energetics, in combination with phonon mode calculations and molecular dynamics simulations, indicate that the syntheses of these freestanding 2D sheets could be selective, with the single- to few-layer WZ110, WZ100, and ZB110 sheets being favored. Through the GW approximation, it is found that all single-layer sheets have large band gaps falling into the ultraviolet range, while thicker sheets in general have reduced band gaps in the visible and ultraviolet range. Onmore » the basis of the present work and the experimental studies on freestanding double-layer sheets of ZnSe, we envision that the freestanding 2D layered sheets of CdX predicted herein are potential synthesis targets, which may offer tunable band gaps depending on their structural features including surface corrugations, stacking motifs, and number of layers.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1136381
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry C
Additional Journal Information:
Journal Volume: TBD
Country of Publication:
United States
Language:
English

Citation Formats

Zhou, Jia, Huang, Jingsong, Sumpter, Bobby G, Kent, Paul R, Xie, Yu, Terrones Maldonado, Humberto, and Smith, Sean C. Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides. United States: N. p., 2014. Web. doi:10.1021/jp504299e.
Zhou, Jia, Huang, Jingsong, Sumpter, Bobby G, Kent, Paul R, Xie, Yu, Terrones Maldonado, Humberto, & Smith, Sean C. Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides. United States. https://doi.org/10.1021/jp504299e
Zhou, Jia, Huang, Jingsong, Sumpter, Bobby G, Kent, Paul R, Xie, Yu, Terrones Maldonado, Humberto, and Smith, Sean C. 2014. "Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides". United States. https://doi.org/10.1021/jp504299e.
@article{osti_1136381,
title = {Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides},
author = {Zhou, Jia and Huang, Jingsong and Sumpter, Bobby G and Kent, Paul R and Xie, Yu and Terrones Maldonado, Humberto and Smith, Sean C},
abstractNote = {Two-dimensional (2D) nanocrystals of CdX (X = S, Se, Te) typically grown by colloidal synthesis are coated with organic ligands. Recent experimental work on ZnSe showed that the organic ligands can be removed at elevated temperature, giving a freestanding 2D sheet of ZnSe. In this theoretical work, freestanding single- to few-layer sheets of CdX, each possessing a pseudo honeycomb lattice, are considered by cutting along all possible lattice planes of the bulk zinc blende (ZB) and wurtzite (WZ) phases. Using density functional theory, we have systematically studied their geometric structures, energetics, and electronic properties. A strong surface distortion is found to occur for all of the layered sheets, and yet all of the pseudo honeycomb lattices are preserved, giving unique types of surface corrugations and different electronic properties. The energetics, in combination with phonon mode calculations and molecular dynamics simulations, indicate that the syntheses of these freestanding 2D sheets could be selective, with the single- to few-layer WZ110, WZ100, and ZB110 sheets being favored. Through the GW approximation, it is found that all single-layer sheets have large band gaps falling into the ultraviolet range, while thicker sheets in general have reduced band gaps in the visible and ultraviolet range. On the basis of the present work and the experimental studies on freestanding double-layer sheets of ZnSe, we envision that the freestanding 2D layered sheets of CdX predicted herein are potential synthesis targets, which may offer tunable band gaps depending on their structural features including surface corrugations, stacking motifs, and number of layers.},
doi = {10.1021/jp504299e},
url = {https://www.osti.gov/biblio/1136381}, journal = {Journal of Physical Chemistry C},
number = ,
volume = TBD,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 2014},
month = {Wed Jan 01 00:00:00 EST 2014}
}