Broadband blue light emissions of one-dimensional hybrid Cu(I) halides with ultrahigh anti -water stability

Low-dimensional organic-inorganic hybrid lead halide perovskites have attracted much interest in solid-state lighting and displays, but the toxicity and instability of lead halide are obstacles to their industrial applications, which must be overcome. As an alternative, Cu(I)-based hybrid metal halides have emerged as a new type of luminescent material owing to their diversified structure, adjustable luminescence, low toxicity and low cost. Herein, we report three one-dimensional (1D) hybrid Cu(I)-based halides with the general formula ACu2Br4 (A = [(Me)4-Pipz]2+ and [BuDA]2+ and [TMEDA]2+). These 1D hybrid Cu(I) halides display stable broadband blue emission with maximum emission peaks in the range of 445-474 nm and the highest photoluminescence quantum yield of 37.8%. Furthermore, in-depth experimental and theoretical investigations revealed that the broadband blue emissions originate from the radiative recombination of self-trapped excitons. Most importantly, there is no structural degradation and attenuation of emission intensity even after continuously soaking these halides in water for at least two months, demonstrating their ultra-high anti-water stability. Hirshfeld surface analysis shows that a large number of weak hydrogen bonds can protect the inorganic skeleton from degradation due to water. This work provides a new strategy for the design of water-stable Cu(I)-based halides with efficient blue emission and wide potential applications in humid environments.

Crystal structure of hexa-glycinium dodeca-iodo-triplumbate

The crystal structure of hexa-glycinium tetra-μ-iodido-octa-iodido-triplumbate, (C2H6NO2)6[Pb3I12] or (GlyH)6[Pb3I12], is reported. The compound crystallizes in the triclinic space group P. The [Pb3I12]6- anion is discrete and located around a special position: the central Pb ion located on the inversion center is holodirected, while the other two are hemidirected. The supra-molecular nature is mainly based on C-H⋯I, N-H⋯I, O-H⋯I and N-H⋯O hydrogen bonds. Dimeric cations of type (A +⋯A +) for the amino acid glycine are observed for the first time.

Accurate Dimension Prediction for Low-Dimensional Organic-Inorganic Halide Perovskites via a Self-Established Machine Learning Strategy

Low-dimensional perovskites (LDPs) have enormous potential for the development of advanced optoelectronic devices and tackling the stability issue for the commercial application of perovskites. However, quantified structural dimensionality prediction for LDPs is still an intractable issue. Herein, we develop a self-established machine learning (ML)-assisted approach to predict the dimensionality of LDPs based on 195 reported amines that are classified as two-dimensional, one-dimensional, and zero-dimensional. The optimal K-nearest neighbor model allows us to realize an accuracy rate of 92.3% for the test data set containing 39 reported amines. Two features, i.e., ATSC1pe and SlogP_VSA2, associated with polarity and electrostatic potential on the van der Waals surface of an organic spacer, are identified from >1800 descriptors as key controlling factors determining the structure dimensionality. This work develops a typical paradigm for the application of a multiple-classification strategy of ML with an extremely high accuracy rate, which would thereby motivate the development of new types of LDPs.

Water-Stable Hybrid Lead-Free Perovskite for Negative Temperature Coefficient Thermistors

Negative temperature coefficient (NTC) thermistors feature higher sensitivities and faster response speeds and thereby have particular applications in many fields. However, current NTC thermistors are mostly based on inorganic ceramic materials, which show obvious drawbacks in material synthesis, property modulation, and flexible film fabrication. Herein, we report, for the first time, the promising application of an inorganic-organic hybrid NTC thermistor. A new lead-free hybrid iodo bismuthate [1,1',1″-(benzene-1,3,5-triyl)tris(3-methyl-1H-imidazol-3-ium)]Bi₂I₉ [denoted as (Me₃TMP)Bi₂I₉] was synthesized by a "double-free" strategy. (Me₃TMP)Bi₂I₉ features a lead-free binuclear bismuth iodine anion charge compensated by a "classic hydrogen-bond-free" cation. (Me₃TMP)Bi₂I₉ exhibits remarkable stability in water and UV light irradiation and shows the largest temperature sensitivity coefficient among all reported NTC materials. Theoretical calculation and detailed structural analysis disclose that the seriously distorted (BiI₆) octahedra are responsible for the intriguing NTC effect for (Me₃TMP)Bi₂I₉.

Organic cation directed hybrid lead halides of zero-dimensional to two-dimensional structures with tunable photoluminescence properties

A series of new inorganic–organic hybrid lead halides have been solvothermally synthesized and characterized with tunable luminescence properties from yellow, orange to red emissions with the largest reported Stokes shift.

New photoluminescent iodoargentates with bisimidazole derivatives as countercations

In this article, three bisimidazole derivatives (1,4-bis(2-ethylimidazol-1-yl)butane, L1; 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl, L2′; and 1,3-bis(2-ethylimidazol-1-yl)propane, L3) were employed to solvothermally react with AgI in an acidic environment, creating three new 1-D chained iodoargentates [H(L1)][Ag₅I₆]·DMF (DMF = N,N′-dimethylformamide) 1, [L2][Ag₃I₅] (L2²⁺ = 4,4′-di(1H-imidazol-1-ium)-1,1′-biphenyl) 2, and [H₂(L3)][Ag₂I₄] 3. L2²⁺ in 2 originated from the in situ N-alkylation of L2′ with the CH₃OH solvent. X-ray single-crystal diffraction analysis reveals that (i) in 1, Ag⁺ and I⁻ aggregate to form a 1-D tube-like iodoargentate, which exhibits the same topology as the carbon tube; (ii) the chain structure of the iodoargentate in 2 is based on a kind of trinuclear Ag–I cluster, which can be viewed as a segment of the classical cubic M₄I₄ cluster; (iii) the chain structure of the iodoargentate in 3 is simple, which can be described as a linear arrangement of the AgI₄ tetrahedra by sharing edges. The photoluminescence analysis reveals that at 77 K, (i) 1 and 2 emit strong yellow light with ms-grade photoluminescence lifetimes (5.460 ms for 1, 6.931 ms for 2); (ii) 3 possesses photochromic luminescence properties. Upon excitation at 254 nm, it emits blue-green light, whereas upon excitation at 365 nm, it emits yellow light.

Three bisimidazole-based chained iodoargentates were solvothermally synthesized, and their photoluminescent behaviors at different temperatures were investigated. Of those, 3 has been found to possess photochromic luminescence properties.

Syntheses, structures and efficient visible light-driven photocatalytic properties of layered cuprous halides based on two types of building units

The exploration of metal halides driven by in situ N-alkylation of TPT derivatives resulted in three layered cuprous halides, which show narrow band gaps and stable visible light-driven photocatalytic properties.