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Lead‐free halide perovskites (LHP) have attracted extensive attention in the field of next‐generation solid‐state lighting. However, single perovskite phosphor with tunable white‐light emission and ultra‐high photoluminescence quantum yield (PLQY) are rare. Here, the tunable dual‐color emission LHP phosphor is developed with a near‐unity PLQY of 99.5%. The LHP phosphor comprises Cs2NaInCl6: Sb3+/Bi3+ and Cs2InCl5·H2O: Sb3+/Bi3+ crystals, with the transition between these two perovskite structures being adjustable by the concentration of Na+. The addition of NaCl inhibits the hydrolysis of the [Sb(H2O)Cl5]2− octahedron, resulting in 3D connected [SbCl6]3− octahedron with less Jahn‐Teller distortion, and the PLQY of LHP is greater than 90%. Finally, the white‐light diode device is fabricated by assembling the LHP with a ultraviolet light‐emitting diode  chip and the white light‐emitting diode device achieved Commission Internationale de l'Eclairage color coordinates of (0.34, 0.33), correlated color temperature of 4936 K, and a high color rendering index of 92.9. The LHP perovskite exhibited multimodal luminescence when excited by 365, 335, and 310 nm UV light, showing the multi‐mode anti‐counterfeiting capabilities of the LHP crystals. [ABSTRACT FROM AUTHOR]

In this work, ZnO-CuO core-shell hybrid nanospheres with well-crystalline wurzite ZnO core and monoclinic CuO shell were successfully synthesized through a two-stage solution process. The as-prepared nanocomposites were carefully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and UV/Vis diffuse reflection spectroscopy (DRS). Compared with bare ZnO cores, the ZnO-CuO core-shell 0-dimensional nanocomposites had greatly enhanced absorption strength and dramatically broadened optical response ranging from near-ultraviolet to visible light, which was probably attributed to heterojunction between n-ZnO core and p-CuO shell and defects originated from synthetic procedure. The as-synthesized p-CuO/n-ZnO core-shell hybrid structure may lead to tantalizing applications including solar energy materials, LED and optical sensor.

Metal halide perovskite (MHP) single crystals (SCs) have been demonstrated to have significant potential in photodetectors and photovoltaic devices due to their exceptional optoelectronic properties. The most promising approach for large-scale fabrication of high-quality MHP SCs is the synthesis of MHP SCs in solution. To explain the mechanism and guide the crystal growth process, the classical nucleation-growth theory was established. However, it mainly focuses on zone melting systems and does not account for the interaction between perovskite and solvent. In this review, we specifically focus on the difference in the growth mechanism between MHP SCs in solution and traditional SCs synthesized by the melting method, which includes a discussion of the dissolution, nucleation, and growth processes. We then summarize recent advances in the preparation of MHP SCs based on the special growth mechanism of the perovskite system. The purpose of this review is to provide comprehensive information to offer targeted theoretical guidance as well as unified understanding for the preparation of high-quality MHP SCs in solution. [ABSTRACT FROM AUTHOR]

Infrared evanescent wave sensing based on chalcogenide fiber is an emerging technology for qualitative and quantitative analysis of most organic compounds. Here, a tapered fiber sensor made from Ge10As30Se40Te20 glass fiber was reported. The fundamental modes and intensity of evanescent waves in fibers with different diameters were simulated with COMSOL. The 30 mm length tapered fiber sensors with different waist diameters, 110, 63, and 31 μm, were fabricated for ethanol detection. The sensor with a waist diameter of 31 μm has the highest sensitivity of 0.73 a.u./% and a limit of detection (LoD) of 0.195 vol.% for ethanol. Finally, this sensor has been used to analyze alcohols, including Chinese baijiu (Chinese distilled spirits), red wine, Shaoxing wine (Chinese rice wine), Rio cocktail, and Tsingtao beer. It is shown that the ethanol concentration is consistent with the nominal alcoholicity. Moreover, other components such as CO2 and maltose can be detected in Tsingtao beer, demonstrating the feasibility of its application in detecting food additives. [ABSTRACT FROM AUTHOR]

Organic‐inorganic hybrid perovskites have demonstrated excellent performance in converting X‐ray photons to electrical signals with high detectivity and sensitivity. Solution‐processed large‐area perovskite polycrystalline thick film is promising for scalable X‐ray flat panel detection imaging. However, ionic migration is severe due to the numerous grain boundaries and pinholes in the thick films, resulting in a large dark current and serious baseline drift. Herein, a new strategy is proposed to suppress the ion migration by inserting 2D Ruddlesden–Popper layer into the 3D perovskite film. The quasi‐2D perovskite thick films exhibit lower defects density, suppressed ion migration, and higher thermal stability compared to their 3D counterpart. Based on these advantages, the quasi‐2D perovskite‐based X‐ray detector shows a sensitivity of 10 860 µC Gyair−1 cm−2 with a stable dark current and photocurrent response. Impressively, the extra‐low detection limit of 69 nGyair s−1 is the lowest in all those reported polycrystalline film‐based detectors. The quasi‐2D film is believed to be a very promising choice for digital flat detectors for sensitive radiation detection and low‐dose dosimeter. [ABSTRACT FROM AUTHOR]