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Title: Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu 3–xSe 2

Abstract

The two-dimensional material KCu 3–xSe 2 was synthesized using both a K 2Se 3 flux and directly from the elements. It crystallizes in the CsAg 3S 2 structure (monoclinic space group C2/m with a = 15.417(3) Å, b = 4.0742(8) Å, c = 8.3190(17) Å, and β = 112.94(3)°), and single-crystal refinement revealed infinite copper-deficient [Cu 3–xSe 2]– layers separated by K + ions. Thermal analysis indicated that KCu 3–xSe 2 melts congruently at ~755 °C. UV–vis spectroscopy showed an optical band gap of ~1.35 eV that is direct in nature, as confirmed by electronic structure calculations. Electronic transport measurements on single crystals yielded an in-plane resistivity of ~6 × 10 –1 Ω cm at 300 K that has a complex temperature dependence. The results of Seebeck coefficient measurements were consistent with a doped p-type semiconductor (S = +214 μV K –1 at 300 K), with doping being attributed to copper vacancies. Transport is dominated by low-mobility (on the order of 1 cm 2 V –1 s –1) holes caused by relatively flat valence bands with substantial Cu 3d character and a significant concentration of Cu ion vacancy defects (p ~ 10 19 cm –3) in this material. In conclusion,more » electronic band structure calculations showed that electrons should be significantly more mobile in this structure type.« less

Authors:
ORCiD logo [1];  [2];  [3];  [1];  [1]; ORCiD logo [3]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); German Research Foundation (DFG)
OSTI Identifier:
1393193
Grant/Contract Number:
AC02-06CH11357; STU 695/1-1
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 14; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Rettie, Alexander J. E., Sturza, Mihai, Malliakas, Christos D., Botana, Antia S., Chung, Duck Young, and Kanatzidis, Mercouri G. Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2. United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.7b02117.
Rettie, Alexander J. E., Sturza, Mihai, Malliakas, Christos D., Botana, Antia S., Chung, Duck Young, & Kanatzidis, Mercouri G. Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2. United States. doi:10.1021/acs.chemmater.7b02117.
Rettie, Alexander J. E., Sturza, Mihai, Malliakas, Christos D., Botana, Antia S., Chung, Duck Young, and Kanatzidis, Mercouri G. Wed . "Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2". United States. doi:10.1021/acs.chemmater.7b02117.
@article{osti_1393193,
title = {Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2},
author = {Rettie, Alexander J. E. and Sturza, Mihai and Malliakas, Christos D. and Botana, Antia S. and Chung, Duck Young and Kanatzidis, Mercouri G.},
abstractNote = {The two-dimensional material KCu3–xSe2 was synthesized using both a K2Se3 flux and directly from the elements. It crystallizes in the CsAg3S2 structure (monoclinic space group C2/m with a = 15.417(3) Å, b = 4.0742(8) Å, c = 8.3190(17) Å, and β = 112.94(3)°), and single-crystal refinement revealed infinite copper-deficient [Cu3–xSe2]– layers separated by K+ ions. Thermal analysis indicated that KCu3–xSe2 melts congruently at ~755 °C. UV–vis spectroscopy showed an optical band gap of ~1.35 eV that is direct in nature, as confirmed by electronic structure calculations. Electronic transport measurements on single crystals yielded an in-plane resistivity of ~6 × 10–1 Ω cm at 300 K that has a complex temperature dependence. The results of Seebeck coefficient measurements were consistent with a doped p-type semiconductor (S = +214 μV K–1 at 300 K), with doping being attributed to copper vacancies. Transport is dominated by low-mobility (on the order of 1 cm2 V–1 s–1) holes caused by relatively flat valence bands with substantial Cu 3d character and a significant concentration of Cu ion vacancy defects (p ~ 1019 cm–3) in this material. In conclusion, electronic band structure calculations showed that electrons should be significantly more mobile in this structure type.},
doi = {10.1021/acs.chemmater.7b02117},
journal = {Chemistry of Materials},
number = 14,
volume = 29,
place = {United States},
year = {Wed Jun 21 00:00:00 EDT 2017},
month = {Wed Jun 21 00:00:00 EDT 2017}
}

Journal Article:
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  • The reaction of (triphos)RhCl(/eta//sup 2/-CSe/sub 2/) (1) in CH/sub 2/Cl/sub 2/ with PEt/sub 3/ gives the phosphoniodiselenoformate complex (triphos)RhCl(Se/sub 2/CPEt/sub 3/) (2). Compound 2 reacts at room temperature in CH/sub 2/Cl/sub 2/ solution with dioxygen to yield OPEt/sub 3/ and (triphos)RhCl(Se/sub 2/CO) (3). The chloride ligand can be removed from 3 in CH/sub 2/Cl/sub 2/ by NaBPh/sub 4/ in 1-butanol to give the 16-electron complex ((triphos)Rh(Se/sub 2/CO))BPh/sub 4/ x 0.5CH/sub 2/Cl/sub 2/ x 0.5C/sub 4/H/sub 9/OH (4), which photochemically or thermally undergoes the chelotropic elimination of CO to form the bis(..mu..-diselenium) complex ((triphos)Rh(..mu..-Se/sub 2/)/sub 2/Rh(triphos))(BPh/sub 4/)/sub 2/ x 2DMF (5b).more » The crystal structures of 4 and 5b have been determined by x-ray crystallography and the results are presented here. The structure consists of monomeric complex cations ((triphos)Rh(Se/sub 2/CO))/sup +/, BPh/sub 4//sup -/ anions, and some amount of CH/sub 2/Cl/sub 2/ and 1-butanol molecules of crystallization. The metal atom is five-coordinated by the three phosphorus atoms of triphos and by the two selenium atoms of the diselenocarbonate ligand in a distorted-square-pyramidal environment. The structure consists of binuclear ((triphos)Rh(..mu..-Se/sub 2/)/sub 2/Rh(triphos))/sup 2 +/ cations, BPh/sub 4//sup -/ anions, and DMF molecules of crystallization. The system consists of two (triphos)Rh(/eta//sup 2/-Se/sub 2/) fragments related by a crystallographic inversion center. Each rhodium atom is coordinated by the three phosphorus atoms of triphos, an /eta//sup 2/-diselenium molecule, and one selenium atom from the other (triphos)Rh(/eta//sup 2/-Se/sub 2/) moiety. 27 references, 3 figures, 5 tables.« less
  • The synthesis, structural characterization, and reactivity of heavier metal polychalcogenide (i.e. polyselenide and polytelluride) compounds are currently an active area of research after intense studies on metal polysulfides in the last decade. Recently, the authors reported on the chemistry of silver-polyselenide complexes, a system characterized by great structural diversity. Furthermore, their preliminary exploration on the Au/Se{sub x}{sup 2{minus}} system revealed an intriguing and unanticipated redox chemistry. This interesting redox interplay between Au{sup n+} (n = 1,3) and Se{sub x}{sup 2{minus}} incited them to investigate further this system in order to gain more information and insight into the redox behavior ofmore » gold in the presence of Se{sub x}{sup 2{minus}} ligands. In order to influence the aforementioned redox chemistry, they examined the reactivity of AuCN toward less reducible shorter polyselenide Se{sub x}{sup 2{minus}} ligands (i.e. x = 1-4) in the presence of different counterions such as Ph{sub 4}P{sup +}, ((Ph{sub 3}P){sub 2}N){sup +}, Pr{sub 4}N{sup +}, etc. Here they wish to report the newly isolated (Ph{sub 4}P){sub 2}(Au{sub 2}(Se{sub 2})(Se{sub 3})) (I), ((Ph{sub 3}P){sub 2}N){sub 2}(Au{sub 2}(Se{sub 2})(Se{sub 3})) (II), and (Ph{sub 4}P){sub 2}(Au{sub 2}(Se{sub 2})(Se{sub 4})) (III), the first Au(I) polyselenide complexes isolated from solution.« less
  • The reaction of InCl[sub 3] with Na[sub 2]Se[sub 5] in dimethylformamide (DMF) in the presence of Ph[sub 4]PCl gave (Ph[sub 4]P)[sub 4][In[sub 2](Se[sub 4])[sub 4](Se[sub 5])] (I) in 75% yield. Under the same conditions, InCl[sub 3] reacted with Na[sub 2]Se[sub 5] in the presence of Pr[sub 4]NBr or Et[sub 4]NBr and afforded (Pr[sub 4]N)[sub 4][In[sub 2](Se[sub 4])[sub 4](Se[sub 5])] (II) in 65% yield and (Et[sub 4]N)[sub 4][In[sub 2](Se[sub 4])[sub 4](Se[sub 5])] (III) in 72% yield, respectively. Single-crystal X-ray diffraction studies show that (I), (II), and (III) contain the same anion, [In[sub 2](Se[sub 4])[sub 4](Se[sub 5])][sup 4[minus]]. The anion consists ofmore » In[sup 3+] centers in trigonal bipyramidal coordination; each In atom is chelated by two bidentate Se[sub 4][sup 2[minus]] ligands forming a [In(Se[sub 4])[sub 2]][sup [minus]] unit. Two of these [In(Se[sub 4])[sub 2]][sup [minus]] units are bridged by an Se[sub 5][sup 2[minus]] chain forming a dimer. The hydrothermal reaction of InCl[sub 3] with Na[sub 2]Se[sub 4] in the presence of Pr[sub 4]NBr and water at 110[degrees]C for 3 days in an evacuated sealed Pyrex tube afforded deep red crystals of (Pr[sub 4]N)[sub 2][In[sub 2]Se[sub 2](Se[sub 4])[sub 2]] (IV), in 80% yield. Under the same conditions the reaction with [(Ph[sub 3]P)[sub 2]N]Cl yields [(Ph[sub 3]P)[sub 2]N][sub 2][In[sub 2]Se[sub 2](Se[sub 4])[sub 2]] (V) in 60% yield. Single-crystal X-ray diffraction studies show that (IV) and (V) contain the same binuclear anion [In[sub 2]Se[sub 2](Se[sub 4])[sub 2]][sup 2[minus]]. The reaction of InCl[sub 3] with Na[sub 2]Se[sub 5] in 1:2 mole ratio in acetonitrile in the presence of Et[sub 4]NBr afforded (Et[sub 4]N)[sub 3][In[sub 3]Se[sub 3](Se[sub 4])[sub 3]] (VI). Similar reaction of TlCl with Na[sub 2]Se[sub 5] in 1:2 mole ratio in DMF in the presence of Et[sub 4]NBr gave (Et[sub 4]N)[sub 3][Tl[sub 3]Se[sub 3](Se[sub 4])[sub 3]] (VII). 57 refs., 13 figs., 14 tabs.« less