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Title: Entropy-Driven Clustering in Tetrahedrally Bonded Multinary Materials; Article No. 034007

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Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
Report Number(s):
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Applied; Journal Volume: 3; Journal Issue: 3
Country of Publication:
United States

Citation Formats

Zawadzki, P., Zakutayev, A., and Lany, S.. Entropy-Driven Clustering in Tetrahedrally Bonded Multinary Materials; Article No. 034007. United States: N. p., 2015. Web. doi:10.1103/PhysRevApplied.3.034007.
Zawadzki, P., Zakutayev, A., & Lany, S.. Entropy-Driven Clustering in Tetrahedrally Bonded Multinary Materials; Article No. 034007. United States. doi:10.1103/PhysRevApplied.3.034007.
Zawadzki, P., Zakutayev, A., and Lany, S.. 2015. "Entropy-Driven Clustering in Tetrahedrally Bonded Multinary Materials; Article No. 034007". United States. doi:10.1103/PhysRevApplied.3.034007.
title = {Entropy-Driven Clustering in Tetrahedrally Bonded Multinary Materials; Article No. 034007},
author = {Zawadzki, P. and Zakutayev, A. and Lany, S.},
abstractNote = {},
doi = {10.1103/PhysRevApplied.3.034007},
journal = {Physical Review Applied},
number = 3,
volume = 3,
place = {United States},
year = 2015,
month = 3
  • Defects are critical to understanding the electronic properties of semiconducting compounds, for applications such as light-emitting diodes, transistors, photovoltaics, and thermoelectrics. In this review, we describe our work investigating defects in tetrahedrally bonded, multinary semiconductors, and discuss the place of our research within the context of publications by other groups. We applied experimental and theory techniques to understand point defects, structural disorder, and extended antisite defects in one semiconductor of interest for photovoltaic applications, Cu 2SnS 3. We contrast our findings on Cu 2SnS 3 with other chemically related Cu-Sn-S compounds, as well as structurally related compounds such as Cumore » 2ZnSnS 4 and Cu(In,Ga)Se 2. We find that evaluation of point defects alone is not sufficient to understand defect behavior in multinary tetrahedrally bonded semiconductors. In the case of Cu 2SnS 3 and Cu 2ZnSnS 4, structural disorder and entropy-driven cation clustering can result in nanoscale compositional inhomogeneities which detrimentally impact the electronic transport. Therefore, it is not sufficient to assess only the point defect behavior of new multinary tetrahedrally bonded compounds; effects such as structural disorder and extended antisite defects must also be considered. Altogether, this review provides a framework for evaluating tetrahedrally bonded semiconducting compounds with respect to their defect behavior for photovoltaic and other applications, and suggests new materials that may not be as prone to such imperfections.« less
  • The ionization energy of ferrocene (Cp{sub 2}Fe) was measured by charge-transfer equilibria as 6.81 {plus minus} 0.07 eV (157.1 {plus minus} 1.6 kcal/mol). The proton affinity was obtained from equilibrium temperature studies as 207 {plus minus} 1 kcal/mol. The protonation of Cp{sub 2}Fe also involves a significant entropy change of +6.3 cal/mol{center dot}K. Deuteration experiments show that, in the protonation of Cp{sub 2}Fe, the incoming proton goes to a sterically unique position and does not exchange with the ring protons. This is consistent with protonation on iron, but ring protonation exclusively in an exo position or an agostic ring-to-iron bridgedmore » structure are also possible. The results suggest that the proton affinity at Fe is greater by at least 5 kcal/mol than for ring protonation. The solvation energies of Cp{sub 2}Fe{sup +} and Cp{sub 2}FeH{sup +} by a CH{sub 3}CN molecule, 11.4 and 12.9 kcal/mol, respectively, are weaker than those of most gas-phase cations, and the attachment energies of dimethyl ether and benzene, <9 kcal/mol, are even weaker. These results support that the weak solution basicity of Cp{sub 2}Fe is due to inefficient ion solvation. The kinetics of proton transfer between Cp{sub 2}Fe and some cyclic compounds is unusually slow, with reaction efficiencies of 0.1-0.01, without significant temperature dependence. These are the first proton-transfer reactions to show such behavior, which may be due to a combination of an energy barrier and steric hindrance. Proton transfer is also observed from (RCN){sub 2}H{sup +} dimer ions to Cp{sub 2}Fe. These reactions may be direct or involve ligand switching, and in several cases either mechanism is endothermic and entropy-driven.« less
  • Electron field emission from two amorphous, tetrahedrally bonded diamondlike carbon films, one with ({ital a}-{ital t}C:N), and a second without nitrogen doping ({ital a}-{ital t}C), prepared by pulsed laser deposition has been investigated using a scanning probe apparatus with micrometer spatial resolution. Electric fields of 100 V/{mu}m (180 V/{mu}m) were required to initiate emission from our {ital a}-{ital t}C:N ({ital a}-{ital t}C) films; however, once emission was established at a particular location, electrons could be drawn at average fields as low as 10 V/{mu}m (60 V/{mu}m) from the same region. The initiation of emission was concomitant with electrical discharges whichmore » were observed by video techniques. These discharges left craters with micrometer dimensions on the surfaces of otherwise smooth films. {copyright} {ital 1996 American Vacuum Society}« less