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Low-dimensional tin-based halide perovskites are considered as eco-friendly substitutions of the iconic lead-based perovskites to host the potential as optoelectronic materials. However, a fundamental understanding of the structure-property relationship of these Sn(II)-based hybrids is still inadequate due to the limited members of this material family. To our knowledge, there is still lack of reports on a series of Sn(II)-based halide perovskites with the same organic cation but covering chloride, bromide, and iodide. In this work, three new halide perovskites TMPDASnX 4 (X = Cl, Br, I) (TMPDA = N,N, N ', N '-tetramethyl-1,4-phenylenediamine) are successfully synthesized, which provide the ideal paradigm to study the halogen-dependent evolution of the structure and properties of Sn(II)-based hybrid perovskites. Despite sharing the same monoclinic lattice ( P 2 1 / m space group), it is demonstrated that TMPDASnCl 4 adopts a one-dimensional structure composed of a five-coordinated pyramid configuration due to an extremely long Sn···Cl distance, while the typical two-dimensional motif is still maintained in TMPDASnBr 4 and TMPDASnI 4 . The ambient stability is declined in the order from chloride to bromide and then to iodide. TMPDASnCl 4 exhibits a broad-band bluish-white-light emission (centered at 515 nm, full width at half-maximum (fwhm) = 193 nm) with the Commission Internationale de l' Elairage (CIE) coordinates as (0.29, 0.34). Further, the correlated color temperature and color-rendering index were determined as 7617 K and 80.5, respectively. Based on the synthesis of new crystals, our work sheds light on the composition-structure-property relationship of hybrid Sn(II)-based halide perovskites., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Organic-inorganic metal halides (OIMHs) have various crystal structures and offer excellent semiconducting properties. Here, we report three novel OIMHs, (PPA) 6 InBr 9 (PPA = [C 6 H 5 (CH 2 ) 3 NH 3 ] + ), (PBA) 2 SbBr 5 , and (PBA) 2 SbI 6 (PBA = [C 6 H 5 (CH 2 ) 4 NH 3 ] + ), showing typical zero-dimensional (0D) structure, octahedra dimers, and corner-sharing one-dimensional chains and crystallized in the monoclinic system with P 2 1 , P 2 1 / c , and C 2/ c space groups, respectively. (PPA) 6 InBr 9 , (PBA) 2 SbBr 5 , and (PBA) 2 SbI 6 have experimental optical band gaps of ∼3.16, ∼2.24, and 1.48 eV, respectively. (PPA) 6 InBr 9 exhibits bright-orange light emission centered at 642 nm with a full-width at half-maximum of 179 nm (0.51 eV) and a Stokes shift of 277 nm (1.46 eV). After Sb 3+ doping, the peak position did not change, and the photoluminescence quantum yield increased significantly from 9.2 to 53.0%. The efficient emission of Sb:(PPA) 6 InBr 9 stems from the isolated ns 2 luminescent center and strong electron-phonon coupling, making the spin-forbidden 3 P 1 - 1 S 0 observable. By combining commercial blue and green phosphors with orange-red-light-emitting (PPA) 6 In 0.99 Sb 0.01 Br 9 , a white-light-emitting diode was constructed, with the color-rendering index reaching up to 92.3. Our work highlights three novel 0D OIMHs, with chemical doping of Sb 3+ shown to significantly enhance the luminescence properties, demonstrating their potential applications in solid-state lighting.

A new series of compounds, ANi 5 Bi 5.6+δ (where A = K, Rb, and Cs) are discovered with a quasi-one-dimensional (Q1D) [Ni 5 Bi 5.6+δ ] - double-walled column and a coaxial inner one-dimensional Bi atomic chain. The columns are linked to each other by intercolumn Bi-Bi bonds and separated by an A + cation. Typical metallic behaviors with strong correlation of itinerant electrons and the Sommerfeld coefficient enhanced with the increasing cationic radius were experimentally observed and supported by first-principles calculations. Compared to AMn 6 Bi 5 (where A = K, Rb, and Cs), the enhanced intercolumn distances and the substitution of Ni for Mn give rise to strong diamagnetic susceptibilities in ANi 5 Bi 5.6+δ . First-principles calculations reveal possible uncharged Ni atoms with even number of electrons in ANi 5 Bi 5.6+δ , which may explain the emergence of diamagnetism. ANi 5 Bi 5.6+δ , as Q1D diamagnetic metals with strong electron correlation, provide a unique platform to understand exotic magnetism and explore novel quantum effects.

The newly discovered AMnBi 2 (A = Ca, Sr, Ba, Eu, and Yb) materials composed of two-dimensional Bi square nets provide an excellent platform to investigate the effect of magnetism on topological band structures. Effectively tuning the magnetic interaction in AMnBi 2 is of great importance to advance this issue. Here, we describe an effective route to tune the magnetism in Dirac semimetal CaMnBi 2 through Cu doping. Structural analysis on CaMn 1- x Cu x Bi 2 single crystals indicates that Cu atoms occupy the Mn sites randomly, with the maximum doping level of 25%. After Cu doping, the Bi square net in charge of the Dirac band is still retained, but the Bi-Bi bond distance is markedly shortened. The antiferromagnetic interaction of CaMnBi 2 is strongly weakened in the Cu-doped crystals, with the transition temperature decreased from 260 to 85 K. On the contrary, the ferromagnetic component that originated from the canted AFM is enhanced, suggesting that the spin canting in this system is tunable. In addition, the magnetoresistance is decreased upon Cu doping, probably due to the disorder in structure. Our work suggests that the CaMn 1- x Cu x Bi 2 (0 ≤ x ≤ 0.25) system can offer a suitable playground to address the interplay between magnetism and the topological state.

Three new lead-free organic-inorganic metal halides (OIMHs) (C 7 H 8 N 3 ) 3 InX 6 ·H 2 O (X = Cl, Br) and (C 7 H 8 N 3 ) 2 SbBr 5 were synthesized. First-principles calculations indicate that the highest occupied molecular orbitals (HOMOs) of the two In-based OIMHs are constituted of π orbitals from [C 7 H 8 N 3 ] + spacers. (C 7 H 8 N 3 ) 3 InX 6 ·H 2 O (X = Cl, Br) shows an indirect optical gap, which may result from this organic-contributed band edge. Despite the indirect-gap nature with extra phonon process during absorption, the photoluminescence of (C 7 H 8 N 3 ) 3 InBr 6 ·H 2 O can still be significantly enhanced through Sb doping, with the internal photoluminescence quantum yields (PLQY) increased 10-fold from 5% to 52%. A white light-emitting diode (WLED) was fabricated based on (C 7 H 8 N 3 ) 3 InBr 6 ·H 2 O:Sb 3+ , exhibiting a high color-rendering index of 90. Our work provides new systems to deeply understand the principles for organic spacer choice to obtain the 0D metal OIMHs with specific band structure and also the significant enhancement of luminescence performance by chemical doping.

The Pb-free hybrid-layered-double perovskites (HLDPs) have been proposed as green and stable semiconducting materials for optoelectronic devices, but the synthesized members are still limited. Here, we report the synthesis of three new HLDPs, (C 8 H 20 N 2 ) 2 AgMBr 8 (M = In, Sb, and Bi), by a solution method using 1,4-bis(ammoniomethyl)cyclohexane (C 8 H 20 N 2 2+ ) as the organic spacing cation. All three of these HLDPs show ⟨100⟩-oriented layered structures with Ag and In/Sb/Bi order arranged in corner-sharing octahedral layers. The first-principle calculations indicate the indirect-gap nature of (C 8 H 20 N 2 ) 2 AgInBr 8 and (C 8 H 20 N 2 ) 2 AgSbBr 8 , while their Bi counterpart shows a direct band gap after considering spin-orbit coupling. The band gaps obtained by diffuse-reflectance spectroscopy are 3.11, 2.60, and 2.70 eV for M = In, Sb, and Bi, respectively. (C 8 H 20 N 2 ) 2 AgInBr 8 shows a broadband red emission centered at 690 nm, and it is mainly attributed to the self-trapped-excitons mechanism. Our results not only provide a series of new "Pb-free" HLDPs with chemical diversity but also help us to further understand the structure-property relationships of HLDP materials.

The reaction of MnTe with AgSbTe 2 in an equimolar ratio (ATMS) provides a new semiconductor, AgMnSbTe 3 . AgMnSbTe 3 crystallizes in an average rock-salt NaCl structure with Ag, Mn, and Sb cations statistically occupying the Na sites. AgMnSbTe 3 is a p-type semiconductor with a narrow optical band gap of ∼0.36 eV. A pair distribution function analysis indicates that local distortions are associated with the location of the Ag atoms in the lattice. Density functional theory calculations suggest a specific electronic band structure with multi-peak valence band maxima prone to energy convergence. In addition, Ag 2 Te nanograins precipitate at grain boundaries of AgMnSbTe 3 . The energy offset of the valence band edge between AgMnSbTe 3 and Ag 2 Te is ∼0.05 eV, which implies that Ag 2 Te precipitates exhibit a negligible effect on the hole transmission. As a result, ATMS exhibits a high power factor of ∼12.2 μW cm -1 K -2 at 823 K, ultralow lattice thermal conductivity of ∼0.34 W m -1 K -1 (823 K), high peak ZT of ∼1.46 at 823 K, and high average ZT of ∼0.87 in the temperature range of 400-823 K.

It is known that as the FeAs 4 tetrahedron in the Fe-based superconductor is close to the regular tetrahedron, critical temperature ( T c ) can be greatly increased. Recently, a Co-based superconductor of LaCoSi (4 K) with "111" structure was found. In this work, we improve the T c of LaCoSi through structural regulation. T c can be increased by the chemical substitution of Co by Fe, while the superconductivity is suppressed by the Ni substitution. The combined analysis of neutron and synchrotron X-ray powder diffractions reveals that the change of the Si-Co-Si bond angles of the CoSi 4 tetrahedron is possibly responsible for the determination of superconducting properties. The Fe chemical substitution is favorable for the formation of the regular tetrahedron of CoSi 4 . The present new Co-based superconductor of LaCoSi provides a possible method to enhance the superconductivity performance of the Co-based superconductors via controlling Co-based tetrahedra similar to those well established in the Fe-based superconductors.

Low-dimensional organic-inorganic metal halides (OIMHs), as emerging light-emitting materials, have aroused widespread attention owing to their unique structural tunability and photoelectric characteristics. OIMHs are also promising materials for optoelectronic equipment, light-emitting diodes, and photodetectors. In this study, (C 3 H 12 N 2 ) 2 Sb 2 Cl 10 (C 3 H 12 N 2 2+ is an N -methylethylenediamine cation), a new zero-dimensional OIMH, has been reported, and (C 3 H 12 N 2 ) 2 Sb 2 Cl 10 possesses a P 2 1 / n space group. The (C 3 H 12 N 2 ) 2 Sb 2 Cl 10 structure contains [Sb 2 Cl 10 ] 4- dimers (composed of two edge-sharing [SbCl 6 ] 3- octahedra) that are surrounded by C 3 H 12 N 2 2+ cations. The experimental band gap of (C 3 H 12 N 2 ) 2 Sb 2 Cl 10 is 3.80 eV, and density functional theory calculation demonstrates that (C 3 H 12 N 2 ) 2 Sb 2 Cl 10 possesses a direct band gap, with the edge of the band gap mainly contributed from the inorganic units. (C 3 H 12 N 2 ) 2 Sb 2 Cl 10 exhibits good ambient and thermal stability. Under 395 nm excitation at room temperature, (C 3 H 12 N 2 ) 2 Sb 2 Cl 10 exhibits a broad emission with a full width at half-maximum of ∼114 nm, peaking at 480 nm, and the broad emission was ascribed to self-trapped exciton emission.

It is known that few Co-based superconducting compounds have been found compared with their Fe- or Ni-based counterparts. In this study, we have found superconductivity of 4 K in the LaCoSi compound for the first time. The combined analysis of neutron and synchrotron X-ray powder diffractions reveals that LaCoSi exhibits an isostructure with the known Fe-based LiFeAs superconductor, which is the first "111" Co-based superconductor. First-principles calculation shows that LaCoSi presents a quasi-two-dimensional band structure that is also similar to that of LiFeAs. The small structural distortion may be more conducive to the emergence of superconductivity in the LaCoSi compound, which provides a direction for finding new Co-based superconducting compounds.

Layered sulfides with high selectivity for binding heavy metal ions and radionuclide ions are promising materials in effluent treatment and water purification. Here we present a rationally designed layered sulfide K x [Bi 4- x Mn x S 6 ] ( x = 1.28) deriving from the Bi 2 Se 3 -structure type by targeted substitution to generate quintuple [Bi 4- x Mn x S 6 ] x - layers and K + cations between them. The material has dual functionality: it is an attractive semiconductor with a bandgap of 1.40 eV and also an environmental remediation ion-exchange material. The compound is paramagnetic, and optical adsorption spectroscopy and DFT electronic structure calculations reveal that it possesses a direct band gap and a work function of 5.26 eV. The K + ions exchange readily with alkali or alkaline-earth ions (Rb + , Cs + , and Sr 2+ ) or soft ions (Pb 2+ , Cd 2+ , Cr 3+ , and Zn 2+ ). Furthermore, when the K + ions are depleted the Mn 2+ ions in the Bi 2 Se 3 -type slabs can also be replaced by soft ions, achieving large adsorption capacities. The ion exchange reactions of K x [Bi 4- x Mn x S 6 ] can be used to create new materials of the type M x [Bi 4- x Mn x S 6 ] in a low temperature kinetically controlled manner with significantly different electronic structures. The K x [Bi 4- x Mn x S 6 ] ( x = 1.28) exhibits efficient capture of Cd 2+ and Pb 2+ ions with high distribution coefficient, K d (10 7 mL/g), and exchange capacities of 221.2 and 342.4 mg/g, respectively. The material exhibits excellent capacities even in high concentration of competitive ions and over a broad pH range (2.5-11.0). The results highlight the promise of the K x [Bi 4- x Mn x S 6 ] ( x = 1.28) phase to serve not only as a highly selective adsorbent for industrial and nuclear wastewater but also as a magnetic 2D semiconductor for optoelectronic applications.

In this work, we report the discovery of a new Ni-based quasi-one-dimensional selenide: Cs 0.9 Ni 3.1 Se 3 . This compound adopts the TlFe 3 Te 3 -type structure with space group P6 3 / m, which consists of infinite [Ni 3 Se 3 ] chains with face-sharing Ni 6 octahedra along the c direction. The lattice parameters are calculated as a = 9.26301(4) Å and c = 4.34272(2) Å, with the Ni-Ni distance in the ab plane as 2.582(3) Å, suggesting the formation of a Ni-Ni metallic bond in this compound. Interestingly, it has been found that Cs 0.9 Ni 3.1 Se 3 is nonstoichiometric, which is different from the other TlFe 3 Te 3 -type phases reported so far. Structure refinement shows that the extra Ni atom in the structure may occupy the 2c site, together with Cs atoms. Cs 0.9 Ni 3.1 Se 3 shows metallic behavior with monotonously decreased resistivity with temperatures from 300 to 0.5 K. Measurements on the magnetic susceptibility display a spin-glass state below 7 K. The specific heat curve gives a Sommerfeld coefficient of 14.6 mJ·K -2 ·mol -1 and a Debye temperature of 143.6 K. The discovery of this new compound enriches the diversity of low-dimensional materials in a transition-metal-based family and also sheds light on the structure-property relationship of this system.