Zero-dimensional lead-free organic–inorganic hybrid metal halides have drawn attention as a result of their local metal ion confinement structure and photoelectric properties. Herein, a lead-free compound of (Gua)3Cu2I5 (Gua = guanidine) with a different metal ion confinement has been discovered, which possesses a unique [Cu2I5]3– face-sharing tetrahedral dimer structure. First-principles calculation demonstrates the inherent nature of a direct band gap for (Gua)3Cu2I5, and its band gap of ∼2.98 eV was determined by experiments. Worthy of note is that (Gua)3Cu2I5 exhibits a highly efficient cool-white emission peaking at 481 nm, a full-width at half-maximum of 125 nm, a large Stokes shift, and a photoluminescence quantum efficiency of 96%, originating from self-trapped exciton emission. More importantly, (Gua)3Cu2I5 single crystals have a reversible thermoinduced luminescence characteristic due to a structural transition scaled by the electron–phonon coupling coefficients, which can be converted back and forth between cool-white and yellow color emission by heating or cooling treatment within a short time. In brief, as-synthesized (Gua)3Cu2I5 shows great potential for application both in single-component white solid-state lighting and sensitive temperature scaling.

Environmental friendly metal hybrid halides show great promise for white light emitting diode (WLED) applications due to their unique optical properties. Herein, a lead-free blue-light excited red-emitting Mn2+-based hybrid halide...

All-inorganic metal halide materials are eye-catching because of their interesting and excellent optoelectronic properties. In this report, a series of Mn 2+ -doped CscdBr 3 perovskite materials were synthesized by grinding in a mortar. The strong photoluminescence (PL) emission band at 650 nm and its PLQY reaches 54.42% after doping with modest Mn 2+ . The enhanced PL emission is the result of a weak ferromagnetic coupling of Mn−Mn pair to form a magnetic polaron and self-trapped exciton (STE), and the energy transfer from the d−d transition of a single Mn to STE and Mn−Mn pair level is very effective. The doping also enhances the nonlinear optical response of the material by their laser excitations. The photophysical mechanism of Mn-doped CsCdBr 3 has been discussed, and the specific conversion process from the bandedge to each charge state has been analyzed in detail. This kind of material may have significant applications in spintronic or optoelectronic devices.

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