Low-dimensional metal halides, such as the CsPb₂X₅ family (X = Cl, Br, I), demonstrate exceptional optoelectronic properties, making them attractive for various applications. In this study, we explore the impact of iodine substitution on the structural, vibrational, and photoluminescence properties of the low-dimensional CsPb₂(Br_1–xI_x)₅ solid solution. Using single-crystal X-ray diffraction, we determined that iodine substitution induces a systematic expansion of the unit cell, affecting bond lengths, layer heights, and distortion angles within the crystal lattice. Raman spectroscopy confirmed these structural changes, revealing softening of vibrational modes and the emergence of new peaks. These findings offer insights into the limits of iodine substitution within the CsPb₂(Br_1–xI_x)₅ solid solution. Photoluminescence studies demonstrated a significant redshift in emission wavelength with increasing iodine content, indicative of a tunable optical bandgap. This change, together with enhanced photoluminescence intensity, can be directly correlated to structural modifications caused by iodine substitution. Our investigation establishes CsPb₂(Br_1–xI_x)₅ compounds as promising candidates for optoelectronic applications. The observed tunability of their optical properties enables the development of tailored devices, such as photodetectors, light-emitting diodes, and other advanced optoelectronic technologies.

中文翻译：

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探索碘取代对低维金属卤化物CsPb2Br5结构和光学性质的影响

低维金属卤化物，例如 CsPb ₂ X ₅系列（X = Cl、Br、I），表现出卓越的光电特性，使其对各种应用具有吸引力。在本研究中，我们探讨了碘取代对低维CsPb ₂ (Br _{1– x} I _x ) ₅固溶体的结构、振动和光致发光性质的影响。使用单晶 X 射线衍射，我们确定碘取代会引起晶胞的系统膨胀，影响晶格内的键长、层高和畸变角。拉曼光谱证实了这些结构变化，揭示了振动模式的软化和新峰的出现。这些发现为了解 CsPb ₂ (Br _{1– x} I _x ) ₅固溶体中碘取代的极限提供了见解。光致发光研究表明，随着碘含量的增加，发射波长发生显着红移，表明光学带隙可调。这种变化加上光致发光强度的增强，可以与碘取代引起的结构修饰直接相关。我们的研究表明 CsPb ₂ (Br _{1– x} I _x ) ₅化合物是光电应用的有希望的候选化合物。观察到的光学特性的可调性使得定制设备的开发成为可能，例如光电探测器、发光二极管和其他先进的光电技术。