Recently, low-dimensional organic−inorganic lead halide perovskites have attracted a great deal of attention due to their outstanding tunable broadband emission, while the toxicity of lead hinders their further application in the photoelectric field.Here, we report a novel lead-free Cu(I)-based organic−inorganic perovskite-related material of a (MA) 4 Cu 2 Br 6 single crystal with zero-dimensional clusters, which is a unique Cu 2 Br 6 4− cornersharing tetrahedron dimer structure consisting of two connected tetrahedra. The single crystal displays a bright broadband green emission with a high photoluminescence with a quantum yield of ≤93%, a large Stokes shift, and a very long (microsecond) photoluminescence (PL) lifetime, resulting from self-trapped exciton emission. The direct band gap characteristic of (MA) 4 Cu 2 Br 6 was proven by density functional theory calculation, and its band gap was determined by experiments to be ∼3.87 eV. In the temperature range of 98−258 K, the PL intensity increases gradually with an increase in temperature due to the deep trapping out of strong electro-phonon coupling, while the PL decreases when the temperature increases over 258 K due to phonon scattering. It is worth mentioning that this new material has high chemical and light stability, in contrast to the lead perovskite.

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Here, we report (C 4 H 9 ) 4 NCuCl 2 single crystals with a luminous intensity that remains largely the same after soaking in water for 24 h. (CH 9 ) 4 NCuCl 2 has a new type zerodimensional framework, in which the isolated [CuCl 2 ] − anions are wrapped by organic (C 4 H 9 ) 4 N + cations. As expected, (C 4 H 9 ) 4 NCuCl 2 shows a broad emission band at 508 nm with a photoluminescence quantum yield of approximately 82% at room temperature, stemming from self-trapped exciton (STE) emission. Temperature-dependent photoluminescence measurement reveals that there is an energy barrier ΔE (24.0 meV) between the intrinsic state and STE state, which leads to the increase in emission intensity with an increase in temperature (98−278 K), while the emission intensity begins to decrease when the temperature is higher than 278 K due to the effects of both thermal quenching and carrier scattering. Our findings provide a new idea for the design of lead-free anti-water stability metal halide materials.

Pb-free perovskite materials, C8H20N2MnBr4 and C4H10NMnBr3 with high luminescence yields, were obtained via a simple mechanochemical process.

Pure transition-metal compounds seldom produce luminescence because of electron correlation and spin–spin coupling. The Pb-free perovskite materials, C 10 H 12 N 2 MnCl 4 and C 5 H 6 NMnCl 3 ·H 2 O, were obtained by using pyridine-implanted manganese chloride lattices. The single-crystal X-ray diffraction indicates their different crystal structures. In C 10 H 12 N 2 MnCl 4 , MnCl 4 cocoordinated with two pyridine molecules forms a lattice composed of independent mononuclear structures with paramagnetic behavior, which shows a clear emission band at 518 nm from the lowest d–d transition of a single Mn(II) ion in the octahedral crystal field. In C 5 H 6 NMnCl 5 ·H 2 O crystal, MnCl 5 ·(H 2 O) x octahedron-cocoordinated with less pyridine molecules than 2 lead to formation arris-share linear chains of Mn-ion octahedra, which give emission band at 620 nm due to the ferromagnetic Mn pair, and ferromagnetism. Pyridine incorporations in the transition-metal halide lattice provide a new channel to modulate the electron correlation and obtain materials with both luminescence and ferromagnetic properties.