Die Kristallstrukturen von Verbindungen des Typs A2TeX6 (A = K, NH4, Rb, Cs; X = Cl, Br, I) / The Crystal Structures of Compounds A2TeX6 (A = K, NH4, Rb, Cs; X = Cl, Br, I)
Abstract:The Crystal Structures of Compounds A 2TeX6 (A = K, N H 4, Rb, Cs; X = Cl, Br, I) W alter Abriel* und Andre du BoisIn stitu t für A norganische C hem ie und SFB 173 d e r U niv ersität H a n n o v e r, C allinstraße 9, D-3000 H a n n o v er 1 Z. N aturforsch. 44b, 1187-1194 (1989); eingegangen am 8. M ärz/20. A pril 1989 T ellu rates, C rystal S tructure, Phase T ran sitio n s, F erroelastics W ith the determ in atio n of the crystal stru ctu re of (N H 4)2T e I6 the list o f the descriptions of A 2T eX 6 s… Show more
“…Tellurium halide perovskites with the general formula A 2 TeX 6 employing ammonia (NH 4 + ), alkali metal cations (K + , Rb + , Cs + ), and thallium (Tl + ) as A-site cation and halide counterions (Cl − , Br − , I − ) were investigated with regard to crystal structure, optical and other physicochemical properties [ 162 , 196 ]. The inorganic tellurium iodide perovskites A 2 TeI 6 (A = K, Rb, Cs, Tl) are especially interesting for photovoltaic applications due to the low band gaps in the range of 1.38–1.52 eV [ 162 ].…”
Section: Heterovalent Substitution With Mono- Tri- and Tetravalent Cmentioning
confidence: 99%
“… Cubic ( Fm m ) – [ 196 ] K 2 TeBr 6 Exp. Monoclinic ( P 2 1 / c ) 2.17 [ 162 , 196 ] Rb 2 TeBr 6 Exp. Cubic ( Fm m ) 2.19 [ 162 ] Cs 2 TeBr 6 Exp.…”
Section: Heterovalent Substitution With Mono- Tri- and Tetravalent Cmentioning
Metal halide perovskites have revolutionized the field of solution-processable photovoltaics. Within just a few years, the power conversion efficiencies of perovskite-based solar cells have been improved significantly to over 20%, which makes them now already comparably efficient to silicon-based photovoltaics. This breakthrough in solution-based photovoltaics, however, has the drawback that these high efficiencies can only be obtained with lead-based perovskites and this will arguably be a substantial hurdle for various applications of perovskite-based photovoltaics and their acceptance in society, even though the amounts of lead in the solar cells are low. This fact opened up a new research field on lead-free metal halide perovskites, which is currently remarkably vivid. We took this as incentive to review this emerging research field and discuss possible alternative elements to replace lead in metal halide perovskites and the properties of the corresponding perovskite materials based on recent theoretical and experimental studies. Up to now, tin-based perovskites turned out to be most promising in terms of power conversion efficiency; however, also the toxicity of these tin-based perovskites is argued. In the focus of the research community are other elements as well including germanium, copper, antimony, or bismuth, and the corresponding perovskite compounds are already showing promising properties.Graphical abstract
“…Tellurium halide perovskites with the general formula A 2 TeX 6 employing ammonia (NH 4 + ), alkali metal cations (K + , Rb + , Cs + ), and thallium (Tl + ) as A-site cation and halide counterions (Cl − , Br − , I − ) were investigated with regard to crystal structure, optical and other physicochemical properties [ 162 , 196 ]. The inorganic tellurium iodide perovskites A 2 TeI 6 (A = K, Rb, Cs, Tl) are especially interesting for photovoltaic applications due to the low band gaps in the range of 1.38–1.52 eV [ 162 ].…”
Section: Heterovalent Substitution With Mono- Tri- and Tetravalent Cmentioning
confidence: 99%
“… Cubic ( Fm m ) – [ 196 ] K 2 TeBr 6 Exp. Monoclinic ( P 2 1 / c ) 2.17 [ 162 , 196 ] Rb 2 TeBr 6 Exp. Cubic ( Fm m ) 2.19 [ 162 ] Cs 2 TeBr 6 Exp.…”
Section: Heterovalent Substitution With Mono- Tri- and Tetravalent Cmentioning
Metal halide perovskites have revolutionized the field of solution-processable photovoltaics. Within just a few years, the power conversion efficiencies of perovskite-based solar cells have been improved significantly to over 20%, which makes them now already comparably efficient to silicon-based photovoltaics. This breakthrough in solution-based photovoltaics, however, has the drawback that these high efficiencies can only be obtained with lead-based perovskites and this will arguably be a substantial hurdle for various applications of perovskite-based photovoltaics and their acceptance in society, even though the amounts of lead in the solar cells are low. This fact opened up a new research field on lead-free metal halide perovskites, which is currently remarkably vivid. We took this as incentive to review this emerging research field and discuss possible alternative elements to replace lead in metal halide perovskites and the properties of the corresponding perovskite materials based on recent theoretical and experimental studies. Up to now, tin-based perovskites turned out to be most promising in terms of power conversion efficiency; however, also the toxicity of these tin-based perovskites is argued. In the focus of the research community are other elements as well including germanium, copper, antimony, or bismuth, and the corresponding perovskite compounds are already showing promising properties.Graphical abstract
“…From the literature, we selected seven ordered stoichiometric inorganic structures accurately determined (with R ≤ 0.1) in single-crystal studies at ambient conditions [32][33][34][35][36]; these structures contain 14 symmetrically independent coordination shells [TeI n ] with no ligands other than I -. The b value was set to 0.37 Å, and the r 0 value was adjusted (with a step of 0.001 Å) to give BVS ≈ Fig.…”
Section: Bond-valence Analysis Of the Crystal Structure Of Cs 2 Teimentioning
The crystal structure of the ternary iodide Cs 2 TeI 6 has been refined by Rietveld analysis of X-ray powder diffraction data. The refinement procedure was stopped when the intensity residual R B = 3.7 % had been reached. Cs 2 TeI 6 crystallizes in the cubic K 2 PtCl 6 structure type, space group Fm-3m (No. 225), with the lattice parameter a = 11.6939(8) Å, Z = 4, D c = 4.797(1) g/cm 3. The reliability of the structural model obtained for Cs 2 TeI 6 in the Rietveld refinement was confirmed by a bond-valence analysis of the structure. For the first time, the bond-valence parameters (r 0 = 2.782 Å and b = 0.37 Å) have been determined for the Te 4+ /Iion pair, from a set of 14 well-determined coordination shells [TeI n ]. These parameters show a reasonably high performance and can be recommended for routine bond-valence analyses of structures containing Te 4+-Ichemical bonds. Ternary halides / Crystal structure / Bond-valence model
“…To our best knowledge, the Te 2 I 10 2- anion represents the first polynuclear tellurium iodide anion reported so far (although tellurium bromide and chloride anions with similar structures have previously been uncovered). − Interestingly, the crystal structure of 1 reveals that the Te 2 I 10 2- dianions interact with one another through extensive I···I contacts, integrating the inorganic anions into a three-dimensional open network (Figure ). These I···I distances (ranging from 3.66 to 3.80 Å) are significantly shorter than the corresponding sum of van der Waals radii (4.0 Å), and figure rather prominently in comparison with the smaller TeI 6 2- systems, where I···I interactions across the TeI 6 2- ions are much weaker (e.g., >4.0 Å). − 2 Packing of the Te 2 I 10 2- anions in the crystal structure of 1 : black spheres, Te; white spheres, I; dashed lines, I···I contacts.…”
The crystal structure of [C(6)H(5)NH(CH(3))(2)](2)Te(2)I(10) consists of the N,N-dimethylanilinium cation and a hitherto unreported tellurium iodide anion Te(2)I(10)(2)(-) [crystal data: C(8)H(12)NTeI(5), monoclinic, P2(1)/c, a = 9.4787(2) A, b = 14.2874(3) A, c = 13.6869(3) A, beta = 95.1918(8) degrees, V = 1845.96(7) A(3), Z = 4]. The Te(2)I(10)(2)(-) dianion is based on two edge-sharing TeI(6)(2)(-) octahedra, and interestingly, it builds up a three-dimensional Te(IV)-I open framework through extensive interconnecting I.I contacts. These I.I contacts (3.66-3.80 A) are significantly shorter than the corresponding sum of van der Waals radii (4.0 A) and may potentially promote charge carrier migration throughout the Te-I network. This material can also be drop-cast into thin films from a heated DMF solution.
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