Sn-based perovskites are the most promising alternative materials for Pb-based perovskites to address the toxicity problem of lead. However, the development of Sn II -based perovskites has been hindered by their extreme instability. Here, we synthesized efficient and stable lead-free Cs 4 SnBr 6 perovskite by using SnF 2 as tin source instead of easily oxidized SnBr 2 . The SnF 2 configures a fluorine-rich environment, which can not only suppress the oxidation of Sn 2 + in the synthesis, but also construct chemically stable SnÀ F coordination to hinder the electron transfer from Sn 2 + to oxygen within the long-term operation process. The SnF 2 -derived Cs 4 SnBr 6 perovskite shows a high photoluminescence quantum yield of 62.8 %, and excellent stability against oxygen, moisture, and light radiation for 1200 h, representing one of the most stable lead-free perovskites. The results pave a new pathway to enhance the optical properties and stability of lead-free perovskite for high-performance light emitters.

Micro light-emitting diodes (μ-LEDs) coupled to color conversion phosphors are among the most promising technologies for future display and artificial light sources. However, current emitters suffer from excessively large particle sizes, preventing micron-scale processability, and/or low stability that hampers the device lifetime. Here, we demonstrate down-conversion μ-LED phosphors based on CsPbBr3 perovskite nanocrystals directly grown inside perfectly sealed mesoporous silica nanospheres (NSs). Key for this advancement is a high-throughput calcination procedure in the presence of K2CO3 as selective pore sealing agent, which simultaneously produces the CsPbBr3 nanocrystals, boosts their emission efficiency to >87%, and perfectly isolates them from the outer environment without causing inter-particle cross-linking or aggregation. This results in size-homogeneous, finely solution-dispersible, ultra-stable, and highly emissive CsPbBr3-SiO2 NSs that fit the technological requirements of photolithographic inks for highly uniform μ-LED color conversion patterns with pixels smaller than 20 μm.

Lead halide perovskite nanocrystals as promising ultrapure emitters are outstanding candidates for the next-generation light-emitting diodes (LED) and display applications, but the thermal quenching behavior of light emission has severely...

Multicomponent systems consisting of lead halide perovskite nanocrystals (CsPbX 3 -NCs, X = Br, I) grown inside mesoporous silica nanospheres (NSs) with selectively sealed pores combine intense scintillation and strong interaction with ionizing radiation of CsPbX 3 NCs with the chemical robustness in aqueous environment of silica particles, offering potentially promising candidates for enhanced radiotherapy and radio-imaging strategies. We demonstrate that CsPbX 3 NCs boost the generation of singlet oxygen species ( 1 O 2 ) in water under X-ray irradiation and that the encapsulation into sealed SiO 2 NSs guarantees perfect preservation of the inner NCs after prolonged storage in harsh conditions. We find that the 1 O 2 production is triggered by the electromagnetic shower released by the CsPbX 3 NCs with a striking correlation with the halide composition (I 3 > I 3−x Br x > Br 3 ). This opens the possibility of designing multifunctional radio-sensitizers able to reduce the local delivered dose and the undesired collateral effects in the surrounding healthy tissues by improving a localized cytotoxic effect of therapeutic treatments and concomitantly enabling optical diagnostics by radio imaging.

Sn‐based perovskites are the most promising alternative materials for Pb‐based perovskites to address the toxicity problem of lead. However, the development of SnII‐based perovskites has been hindered by their extreme instability. Here, we synthesized efficient and stable lead‐free Cs4SnBr6 perovskite by using SnF2 as tin source instead of easily oxidized SnBr2. The SnF2 configures a fluorine‐rich environment, which can not only suppress the oxidation of Sn2+ in the synthesis, but also construct chemically stable Sn−F coordination to hinder the electron transfer from Sn2+ to oxygen within the long‐term operation process. The SnF2‐derived Cs4SnBr6 perovskite shows a high photoluminescence quantum yield of 62.8 %, and excellent stability against oxygen, moisture, and light radiation for 1200 h, representing one of the most stable lead‐free perovskites. The results pave a new pathway to enhance the optical properties and stability of lead‐free perovskite for high‐performance light emitters.