and adjustable bandgap, thereby exhibiting extraordinary X-ray detection performance. [1] To date, high-quality lead-based perovskite single crystals have demonstrated ultrahigh detection performance. However, they are limited by their current shortcomings, including the toxicity of lead, chemical instability, inherent brittleness of bulk crystals, and their hightemperature fabrication and complex processes. [2] Therefore, the development of low-cost, environmentally friendly, flexible X-ray detectors, and novel scintillators still remain a challenge.Owing to the high emission stability, low self-absorption, soft lattice, unique self-trapped exciton emission (STE), [3] and relatively low toxicity and earth-abundant composition, lead-free copper-based halide Cs 3 Cu 2 I 5 nanocrystals (NCs) have attracted extensive attention in the field of optoelectronics, [4] such as electroluminescent lightemitting diode (LED) devices, [5] ultraviolet (UV) photodetectors, [6] X-ray imaging, [7] and anticounterfeiting technology. [8] Although progress has been made in the synthesis and application of Cs 3 Cu 2 I 5 NCs, [9] the insufficient synthesis reaction and difficulty in controlling the crystal size, morphology, and uniformity of Cs 3 Cu 2 I 5 NCs still remain the main obstacles hindering device performance and fundamental research. [10] Metal ion doping is an effective way to tune the structure and optoelectronic properties of materials, which Scintillators are essential for high-energy radiation detection in a variety of potential applications. However, due to complex fabrication processes and nanocrystal homogeneity, conventional scintillators are challenging to meet the need for cost-effective, environmentally friendly, and flexible X-ray detection. Here, monodisperse nanocrystals (NCs) with small grain size and colloidal stability are obtained by adjusting the doping concentration of Zn 2+ ions and controlling the morphology uniformity of Cs 3 Cu 2 I 5 NCs. The photoluminescence quantum yield (PLQY) for the optimal doping concentration is as high as 92.8%, which is a 28.5% improvement compared to nondoped NCs. Density functional theory calculations reveal that the Zn 2+ dopant inclines to occupy Cu sites and the I-rich condition suppresses the formation of I vacancy, enriching the excited electron density at the band-edge to enhance the self-trapped exciton emission. Moreover, high luminescence performance and flexible X-ray scintillator films are prepared using Zn 2+doped Cs 3 Cu 2 I 5 NCs, with a spatial resolution of up to 15.7 lp mm -1 . This work provides an effective strategy for the development of environmentally friendly, low-cost, and efficient blue-emitting 0D all-inorganic metal halides, as well as shows their great potential for high-performance flexible lead-free and low-toxicity X-ray detector applications.

Metal halide perovskites are promising energy materials because of their high absorption coefficients, long carrier lifetimes, strong photoluminescence, and low cost. Low-dimensional halide perovskites, especially one-dimensional (1D) halide perovskite nanowires (NWs), have become a hot research topic in optoelectronics owing to their excellent optoelectronic properties. Herein, we review the synthetic strategies and mechanisms of halide perovskite NWs in recent years, such as hot injection, vapor phase growth, selfassembly, and solvothermal synthesis. Furthermore, we summarize their applications in optoelectronics, including lasers, photodetectors, and solar cells. Finally, we propose possible perspectives for the development of halide perovskite NWs.