Metal halide perovskites have flexible crystal and electronic structures and adjustable emission characteristics, which have very broad applications in the optoelectronic field. Among them, all-inorganic perovskites have attracted more attention than others in recent years because of their characteristics of large diffusion length, high luminescence efficiency, and good stability. In this work, Sb 3+ -doped RbCdCl 3 crystalline powder was synthesized by a simple hydrothermal method, and its luminescence properties were studied, which showed a broad emission band with a large Stokes shift and efficient yellow light emission at about 596 nm at room temperature with a photoluminescence quantum yield of 91.7%. The emission came from the transition of the selftrapped exciton 1 (STE1) out of 3 P n (n = 0, 1, and 2) to S 0 due to strong electron−phonon coupling, which scaled with increasing temperature. Moreover, its emission color became white at low temperatures due to the occurrence of transition of other self-trapped exciton 0 (STE0) state emission out of the 1 S states of Sb ions to S 0 in the lattice. These emission color changes may be used for temperature sensing, and this Sb 3+ -doped RbCdCl 3 material expands the knowledge of the efficient luminescent inorganic material family for further applications of allinorganic perovskites.

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.

All-inorganic metal halide perovskite semiconductor materials have a wide range of potential applications for their excellent optoelectronic properties. Among those metal halides studied, cesium cadmium chloride has not been fully studied. Here, we report the simple synthesis and optical properties of Fe3+ doped CsCdCl3 perovskite powder by the hydrothermal technique; the products give a strong yellow photoluminescence quantum yield up to 63.22%. The powder x-ray diffraction pattern shows that the Fe3+ introduction does not change the hexagonal structure of the host lattice, magnetic characterization indicated direct Fe–Fe ferromagnetic coupling, and the photoluminescence enhancement is due to the overlapping of the self-trapped state and the d–d transition of the ferromagnetic Fe3+ pair, i.e., magnetic polarons.

Metal halide materials have recently sparked intense research because of their excellent photophysical properties and chemical stability. For example, RbCdCl3:Sb3+ exhibits broad emission at about 600 nm with a high photoluminescence quantum yield (PLQY) over 91% and double emission bands with bright white color. Herein, we obtained a novel Rb and Cd layered perovskite Rb3Cd2Cl7 doped with Sb3+, which gives luminescence at 525 nm with a large Stokes shift of 200 nm, originating from a self-trapped exciton (STE). Its PLQY is 57.47%, but its low-temperature PLQY becomes much higher at the same wavelength. When Rb3Cd2Cl7:Sb3+ and RbCdCl3:Sb3+ were compared, the two classes of quantum confinement effects by Rb and Cd ions in the lattice were identified to describe their electronic states and different optical properties. These results suggest that properties of Sb-doped cadmium halides could be modified by the structure type and local atomic confinement to find applications as promising luminescent materials for optoelectronic devices.

Long afterglow luminescent materials have captured intense attention for their unique applications in biological imaging, photodynamic therapy, and optical anti-counterfeiting. However, achieving highly efficient and tunable ultralong afterglow emission in all-inorganic metal halides is an open challenge. Herein, Sb 3+ -doped hexagonal CsCdCl 3 metal halide is reported via hydrothermal reaction. Upon photoabsorption, the as-synthesized compounds exhibit dual-emission bands with a photoluminescence quantum yield (PLQY) of 59.6%, which can be attributed to the self-trapped exciton emission out of the strong electron-phonon coupling. After ceasing excitation of 365 nm, bright afterglow emission with the longest duration lasting up to 5000 s is witnessed in Sb 3+ -doped CsCdCl 3 . More importantly, the color-tunable and time-dependent ultralong afterglow emission is realized via regulating the doping concentration of Sb 3+ , which should be due to the trap electrons increase gradually under high doping concentration. Given this unusual afterglow emission characteristics, the optical anti-counterfeiting and information encryption are constructed based on as-synthesized compounds. These findings not only help further understand the tunable afterglow emission mechanism in all-inorganic metal halides, but also provide a new strategy for designing novel ultralong afterglow luminescent materials.