TY - JOUR
T1 - Spontaneous Non-stoichiometry and Ordering in Degenerate but Gapped Transparent Conductors
AU - Malyi, Oleksandr I.
AU - Yeung, Michael T.
AU - Poeppelmeier, Kenneth R.
AU - Persson, Clas
AU - Zunger, Alex
N1 - Funding Information:
The work of A.Z. and O.I.M. at University of Colorado Boulder, and of K.R.P. and M.T.Y. at Northwestern University, was supported by the NSF-DMR EPM program under grants DMR-1806939 and DMR-1806912, respectively. M.T.Y. would like to thank the Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Solar Energy Technologies Office administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. The ORISE is managed by Oak Ridge Associated Universities (ORAU) under DOE contract number DE-SC00014664. All opinions expressed in this paper are the authors? and do not necessarily reflect the policies and views of DOE, ORAU, or ORISE. O.I.M. and C.P. acknowledge support from the Research Council of Norway (contract no. 251131), and the Norwegian Metacenter for Computational Science (NOTUR) for providing access to supercomputer resources. We would like to thank Zachary Mansley for help with transmission electron microscopy. O.I.M. carried out the theoretical calculations. M.T.Y. fabricated the samples and carried out structure analysis by X-ray powder diffraction. A.Z. directed the design of the research, analysis of the results, and writing of the paper. O.I.M. contributed most to writing of the paper, with contributions from all co-authors. K.R.P. supervised the experimental work. C.P. and A.Z. supervised all theoretical studies. The authors declare no competing interests.
Funding Information:
The work of A.Z. and O.I.M. at University of Colorado Boulder, and of K.R.P. and M.T.Y. at Northwestern University, was supported by the NSF -DMR EPM program under grants DMR-1806939 and DMR-1806912 , respectively. M.T.Y. would like to thank the Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Solar Energy Technologies Office administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. The ORISE is managed by Oak Ridge Associated Universities (ORAU) under DOE contract number DE-SC00014664 . All opinions expressed in this paper are the authors’ and do not necessarily reflect the policies and views of DOE, ORAU, or ORISE. O.I.M. and C.P. acknowledge support from the Research Council of Norway (contract no. 251131 ), and the Norwegian Metacenter for Computational Science (NOTUR) for providing access to supercomputer resources. We would like to thank Zachary Mansley for help with transmission electron microscopy.
Publisher Copyright:
© 2019 Elsevier Inc.
PY - 2019/7/10
Y1 - 2019/7/10
N2 - We highlight a class of materials representing an exception to the Daltonian view that compounds maintain integer stoichiometry at low temperatures and use this behavior to select ordered vacancy compounds (OVCs) striking a wanted compromise between carrier concentration, transparency, and phase stability, crucial for transparent conductors (TCs). We show that carriers in the conduction band (CB) of degenerate gapped BaNbO3, Ca6Al7O16, and Ag3Al22O34 compounds can cause a self-regulating instability, whereby cation vacancies form exothermically because a fraction of the CB electrons decays into the hole states formed by such vacancies, and this electron-hole recombination offsets the positive energy associated with vacancy bond breaking. This Fermi level-induced spontaneous non-stoichiometry can lead to the formation of OVCs with different optoelectronic properties and stable in different ranges of chemical potentials. Thus, we demonstrate how a window of opportunity can be determined between opposing tendencies of transparency, conductivity, and stability to design TCs.
AB - We highlight a class of materials representing an exception to the Daltonian view that compounds maintain integer stoichiometry at low temperatures and use this behavior to select ordered vacancy compounds (OVCs) striking a wanted compromise between carrier concentration, transparency, and phase stability, crucial for transparent conductors (TCs). We show that carriers in the conduction band (CB) of degenerate gapped BaNbO3, Ca6Al7O16, and Ag3Al22O34 compounds can cause a self-regulating instability, whereby cation vacancies form exothermically because a fraction of the CB electrons decays into the hole states formed by such vacancies, and this electron-hole recombination offsets the positive energy associated with vacancy bond breaking. This Fermi level-induced spontaneous non-stoichiometry can lead to the formation of OVCs with different optoelectronic properties and stable in different ranges of chemical potentials. Thus, we demonstrate how a window of opportunity can be determined between opposing tendencies of transparency, conductivity, and stability to design TCs.
KW - MAP 1: Discovery
KW - defects
KW - electrides
KW - non-stoichiometry
KW - optical properties
KW - ordered vacancy compounds
KW - stability
KW - transparent conductors
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U2 - 10.1016/j.matt.2019.05.014
DO - 10.1016/j.matt.2019.05.014
M3 - Article
AN - SCOPUS:85072622817
VL - 1
SP - 280
EP - 294
JO - Matter
JF - Matter
SN - 2590-2393
IS - 1
ER -