Highly efficient blue-emitting three-dimensional (3D) lead−free halide perovskites with excellent stability have attracted worldwide attention. Herein, a doping route was adopted to incorporate Sb 3+ ions into the Cs 2 NaInCl 6 for decorating the electronic band structure. Due to the moderate electron−phonon coupling, the Sb 3+ -doped Cs 2 NaInCl 6 double perovskites showed a narrow and relatively unusual blue emission of self-trapped excitons (STEs). Density functional theory (DFT) calculation indicated that the doped Sb 3+ ions could break the parityforbidden transition rule and modulate the density of state (DOS) population effectively to boost the PLQY of STEs drastically. The optimized Sb 3+ :Cs 2 NaInCl 6 exhibited a PLQY of up to 75.89% and excellent stability under the consecutive illumination of 365 nm UV light for 1000 h. This kind of highly efficient lead-free Sb 3+ -doped Cs 2 NaInCl 6 double perovskites may overcome the bottlenecks of severe toxicity and insufficient stability and therefore have an extensive application in the scarce blue photonic and optoelectronic fields.

As an effective method to improve the optical properties and stability of perovskite matrix, doped halide perovskites have attracted extensive attention in the field of optoelectronic applications. Herein, a series of all inorganic lead-free Te4+-doped Cs2ZrCl6 vacancy-ordered perovskites were successfully synthesized with different Te-doping concentrations by a solvothermal method, and deliberate Te4+-doping results in green-yellow triplet self-trapped exciton (STE) emission with a high photoluminescence quantum yield (PLQY) of 49.0%. The efficient energy transfer was observed from singlet to triplet emission. Further, the effects of A-site Rb alloying on the optical properties and stability were investigated. We found that A-site Rb alloying and C-site cohalogenation did not change the luminescence properties of Te4+, but the addition of a small amount of Rb+ can improve the PL intensity and moisture stability. Our results provide physical insights into the nS2 Te4+-ion-doping-induced emissive mechanism and shed light on improving the environmental stability for further applications.

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Manganese-doped zinc selenide quantum dots (Mn:ZnSe d-dots) with high optical quality, pure dopant emission with 40-60% photoluminescence quantum yield, were synthesized with air-stable and generic starting materials, namely zinc (manganese) fatty acid salts with corresponding free fatty acids, Se powder, fatty amine, and octadecene. The pyrophoric, highly toxic, and expensive organophospines were eliminated from the existing synthetic protocols for high quality Mn:ZnSe d-dots, which changed the reaction profile substantially mainly because of the enhanced reactivity of elemental Se with the presence of fatty amines. The reaction temperatures for two key processes involved in "nucleation-doping", namely, formation of MnSe nanoclusters and their overcoating by the host, were both reduced. Multiple injection techniques were employed to realize balanced diffusion of the Mn ions in the d-dots. The resulting d-dots were found to be in zinc-blende crystal structure, with optimal spherical shape, nearly monodispersed, and controlled in their Mn:Zn ratio.

Lead-free lower-dimensional organic−inorganic metal halide materials have recently triggered intense research because of their excellent photophysical properties and chemical stability. Herein, we report a novel zero-dimensional (0D) organic−inorganic hybrid single crystal (TMA) 2 SbCl 5 •DMF (TMA = N(CH 3 ) 3 , DMF= HCON(CH 3 ) 2 ), which exhibits typical selftrapped exciton (STE) emission with an efficient yellow emission at 630 nm and high photoluminescence quantum yield (PLQY) of 67.2%. The dual STE emission is attributed to the singlet and triplet STEs in inorganic [SbCl 5 ] 2− , respectively. Further, an ab initio molecular dynamics simulation was performed to estimate the stability of crystal structure at room temperature. The calculated excited-state structure indicates that the deformation parameter (Δd) of the excited-state structure is larger than that of the ground state, illustrating the origin of a large Stokes shift. These results indicate that these new 0D lead-free organic−inorganic hybrid metal halides are promising luminescent materials for optoelectronic applications.

Double perovskites exhibit low toxicity, intrinsic thermodynamic stability, and small carrier effective mass. Herein, a novel doping route was adopted to incorporate Mn ions into Cs2Na1–x Ag x BiCl6 double perovskites for engineering the band gap and tailoring the energy transfer. The as-prepared Cs2Na1–x Ag x BiCl6 (0 < x < 1) exhibited excellent photoluminescence and a broad self-trapped exciton (STE) band from 500 to 900 nm, which exhibited an abnormal emission peak blue shift with increasing temperature. For Mn-doped Cs2Na1–x Ag x BiCl6, the two photoluminescence (PL) bands from d–d transition emission of Mn ions and STEs were always observed simultaneously in the PL window. The distinct energy-transfer channel from the Mn2+ ion guest to the double-perovskite host resulted in the dominant Mn2+ emission. Our results will be helpful for further understanding the nature of the photophysics of double perovskites.

High-quality Mn:ZnSe/ZnS core/shell and Mn:ZnSeS shellalloyed doped nanocrystals (d-dots) with up to 50% photoluminescence (PL) quantum yield (QY) have been synthesized based on nucleationdoping strategy through a phosphine-free approach. The formation of MnSe nanoclusters was achieved by adjusting the ratio of stearic acid to manganese stearate and using a highly reactive Se precursor. Mn: ZnSe/ZnS core/shell d-dots were prepared by an epitaxial ZnS growth on the Mn:ZnSe core. The PL QY of Mn:ZnSe/ZnS core/shell d-dots decreased dramatically after injections of S precursor but was completely recovered through an UV irradiation. After annealing at 240 °C for 30 min, the core/shell Mn:ZnSe/ZnS d-dots evolved to the Mn:ZnSeS shell-alloyed d-dots with high PL QY. The PL peak position of the d-dots could be tuned within a relatively large optical window, from 584 to 605 nm.

The thermal stability of luminescence is important for the application of quantum dots (QDs) in light-emitting devices. The temperature-dependent photoluminescence (PL) intensities and decay times of Mn-doped ZnS, ZnSe, and ZnSeS alloyed core-shell QD films were studied in the temperature range from 80 to 500 K by steady-state and time-resolved PL spectroscopy. It was found that the thermal stability of Mn-doped QD emissions was significantly dependent on the shell thickness and the host bandgap, which was higher than that of workhorse CdSe QDs. Nearly no PL quenching took place in Mn:ZnS QDs with a thick ZnS shell, which kept a high PL quantum yield (QY) of ~50% even at 500 K; and the thermally stable PL was also observed in highly luminescent Mn:ZnSe and Mn:ZnSeS QDs with a quenching temperature over 200 °C. Further, the stability of Mn-doped QDs with different shell thickness at high temperature was also examined through heating-cooling cycling experiments. The PL quenching in the thick shell-coated Mn-doped QDs was almost totally recovered. The PL quenching mechanisms of the Mn(2+) ion emissions were discussed.