Novel, stable, and lead-free CsCuBr₂ halides were synthesized and utilized as efficient light emitters.

Cs₄Mn_xCd_1−xSb₂Cl₁₂ exhibit typical Mn²⁺ ion emission based on the efficient energy transfer from the intrinsic dark STE states to the Mn²⁺ ions. Furthermore, we observed an anomalously negative photo-response collapse in a photodetector.

As derivatives of metal halide perovskite materials, low-dimensional metal halide materials have become important materials that have attracted much attention in recent years. As one branch, zinc-based metal halides have the potential for practical applications due to their lead-free, low-toxicity and high-stability characteristics. However, pure zinc-based metal halide materials are still limited by their poor optical properties and cannot achieve large-scale practical applications. Therefore, in this work, we report an organic–inorganic hybrid zero-dimensional zinc bromide, (TDMP)ZnBr₄, using transition metal Mn²⁺ ions as dopants and incorporating them into the (TDMP)ZnBr₄ lattice. The original non-emissive (TDMP)ZnBr₄ exhibits bright green emission under the excitation of external UV light after the introduction of Mn²⁺ ions with a PL peak position located at 538 nm and a PLQY of up to 91.2%. Through the characterization of relevant photophysical properties and the results of theoretical calculations, we confirm that this green emission in Mn²⁺:(TDMP)ZnBr₄ originates from the ⁴T₁ → ⁶A₁ optical transition process of Mn²⁺ ions in the lattice structure, and the near-unity PLQY benefits from highly localized electrons generated by the unique zero-dimensional structure of the host material (TDMP)ZnBr₄. This work provides theoretical guidance and reference for expanding the family of zinc-based metal halide materials and improving and controlling their optical properties through ion doping.

Low-dimensional metal halides with efficient luminescence properties have received widespread attention recently. However, nontoxic and stable low-dimensional metal halides with efficient blue emission are rarely reported. We used a solvothermal synthesis method to synthesize tetravalent zirconium ion-doped all-inorganic zero-dimensional Cs₂ZnCl₄ for the first time. Bright blue emission in the range of 370 nm–700 nm with a emission maximum at 456 nm was observed in Zr⁴⁺:Cs₂ZnCl₄ accompanied by a large Stokes shift, which was due to self-trapped excitons (STEs) caused by the lattice vibrations of the twisted structure. Simultaneously, the PLQY of Zr⁴⁺:Cs₂ZnCl₄ achieve an impressive 89.67%, positioning it as a compelling contender for future applications in blue-light technology.

Lead halide perovskites have been widely used in optoelectronic devices due to their excellent properties; however, the toxicity of lead and the poor stability of these perovskites hinder their further application. Herein, we report a zero-dimensional (0D) lead-free organic manganese (II) bromide hybrid compound of (TBA)₂MnBr₄ (TBA⁺ = tetrabutylammonium cation) single crystals (SCs) with great environmental stability. The (TBA)₂MnBr₄ SCs show a strong green emission peak at 518 nm with a high photoluminescence quantum yield (PLQY) of 84.98% at room temperature, which is attributed to the d-d transition of single Mn²⁺ ions, as also confirmed through density functional calculation. A green light-emitting diode was produced based on (TBA)₂MnBr₄ SCs, which exhibited CIE coordinates (0.17, 0.69) close to those of standard green. A photodetector fabricated by the (TBA)₂MnBr₄ SCs shows an obvious photo response with a rapid millisecond rise/decay response time (at 365 nm). Our findings promote the research of Mn(II)-based organic–inorganic hybrid materials and pave the way by using these materials for future high-performance optoelectronic devices.

A₂BB′X₆ double perovskites offer broad compositional flexibility, requiring screening strategies that jointly consider electronic properties and thermodynamic stability. We developed a leakage-controlled machine learning workflow integrating canonical-formula grouping, robustness tests, descriptor-cost analysis, and prediction uncertainty. The dataset contains 1975 Materials Project entries represented by 398 descriptors. Extra Trees predicted band gaps with a held-out MAE of 0.2031 eV and R² of 0.9437, whereas histogram gradient boosting predicted energy above the hull with an MAE of 0.02122 eV atom⁻¹ and R² of 0.8601. The stability classifier achieved ROC-AUC, PR-AUC, and MCC values of 0.9603, 0.9632, and 0.8192, respectively. Removing 39 relaxed-structure descriptors increased hull-energy MAE by approximately 12.5%, supporting a two-stage workflow of composition-based triage followed by structure-informed refinement. Chemical-distribution-shift tests revealed substantial performance degradation and defined the applicability domain. Seventeen held-out compounds met the screening criteria, representing retrospective recovery rather than prospective discovery. Path-specific phonon calculations for one Tier-1 candidate and two representative Tier-2 fluorides showed no imaginary modes along L–Γ–X–W, but cannot establish full-zone dynamical stability. Their HSE06+SOC gaps of 2.148–2.919 eV exceeded the original 1.0–2.0 eV window, underscoring the need for multi-fidelity validation. Overall, the workflow provides a reproducible and well-defined strategy for prioritizing and validating double perovskites.