The photoluminescence quantum yield (PLQY) of CsPbBr3 perovskite nanocrystals (NCs) prepared by the hot‐injection method can exceed 90%, which have attracted intensive attention for white light‐emitting diodes (WLEDs). However, the whole hot‐injection experiment requires air isolation and relatively high temperature. In addition, the poor stability of CsPbBr3 NCs impedes their applications. Here, a facile method is reported to synthesize CsPbBr3@ZrO2 NCs at room temperature in air. Owing to using ZrO2 coated CsPbBr3 NCs, the prepared CsPbBr3@ZrO2 NCs not only present a PLQY of 80% but also exhibit an enhanced stability to heat and moisture. Furthermore, WLEDs are fabricated with CsPbBr3@ZrO2 NCs and commercial red phosphors (CaAlSiN3:Eu2+) on blue LEDs chips. The fabricated WLEDs exhibit a correlated color temperature (CCT) of 4743 K and luminous efficacy as high as 64.0 Lm W–1. In addition, visible light communication with a high data rate of 33.5 Mbps is achieved using the WLEDs. This work provides a room temperature strategy to coat zirconia for CsPbBr3@ZrO2 NCs, benefiting to enhance the optical performance and stability, as well as the promotion of the great potentials in solid‐state illuminating and visible light communication applications.

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Metal halide perovskite‐based high‐performance X‐ray scintillator is considered as one of the most favorable candidates applied in the fields of medicine, industry, and science. However, the current X‐ray scilltillators based on perovskites still suffer from the issue of poor stability, which impedes their further wide applications. Herein, a template assembled method to prepare large‐size, flexible, and stable CsPbBr3@Polymethyl methacrylate composite films in ambient conditions is developed and their detection performance is studied. The composite films can maintain 94% and 81% of the initial PL intensity after 2000 cycles bending and storing in water over 2520 h, respectively. In addition, the prepared scintillators exhibit not only a low detection limit of 40.1 nGyair s−1 and a high spatial resolution of 8.0 lp mm−1, but also an excellent tolerance against radiation (108 h). Thus, this simple but yet effective method would not doubt pave the way for further development of scintillators and might be well applicable to other metal halides.

Due to their nontoxicity, stability, and unique optoelectronic properties, all‐inorganic lead‐free halide semiconductors with perovskite and perovskite‐like structures have successfully emerged as promising optoelectronic materials for various applications, such as solar cells, light‐emitting diodes (LEDs), photodetectors, and X‐ray detectors. To further explore their practical potentials, researchers have paid more attention in all‐inorganic lead‐free perovskite (‐like) (ILFP) single crystals. For these single crystals, the advantages of large sizes, uniform surface morphology, and few defects can facilitate their excellent performances and practical applications. Besides, compared with the low dimensional and polycrystalline ILFP materials, the ILFP single crystals feature enhanced performances, including a longer carrier diffusion length and a larger light absorption coefficient, which attract a great deal of attention. Therefore, focus is on the researching progress of ILFP single crystals and the development of their preparation methods, as well as the novel properties of ILFP single crystals. In addition, the reported applications of ILFP single crystals are proposed to highlight their practical importance. With the perspective of the evolution and challenges, the current limitations of the materials and devices are discussed, followed by an inspirational outlook on their future development directions.

The poor stability of lead‐free Cs3Cu2Cl5 nanocrystals (NCs) is the main impediment for their broad practical applications. Here, a sol‐gel reaction using tetraethoxysilane (TEOS) as the silica coating precursor to prepare Cs3Cu2Cl5@SiOx NCs is proposed. Due to the efficient passivation and robust protection of SiOx shells on the NCs surface, Cs3Cu2Cl5@SiOx NCs solution and films exhibit a high photoluminescence quantum yield of 98% and 76%, respectively, and improved stability against water and heat. Cs3Cu2Cl5@SiOx NCs are then used to fabricate warm white light‐emitting diodes (WLEDs), which show a high color‐rendering index of 94 and a proper correlated color temperature of 5049 K, and maintain an excellent thermal (265–360 K) and prolonged operating (380 h) stability. In addition, the good white light emission facilitates the application in visible light communication (VLC). The VLC light source demonstrates a −3 dB bandwidth of 420 kHz, and the achieved data rate of the VLC system reaches 2.65 Mbps using orthogonal frequency division multiplexing modulation with a bit loading. As a result, lead‐free Cs3Cu2Cl5@SiOx NCs with an efficient optical performance and an excellent stability might promote the development of stable NCs and extend the applications in optoelectronics.