Hybrid metal halides with nonlinear optical (NLO) and dielectric dual switching properties are a class of materials with great application prospects in the fields of optoelectronics and smart devices. However, effectively modifying and regulating molecular structures to obtain temperature-responsive NLO switching performance is still a challenge. Herein, we reported a strategy to modify symmetry by employing halogen substitution. Br with greater electronegativity reduced the symmetry from the centrosymmetric (Cl-MM)₂MnBr₄ (1) to the noncentrosymmetric (Br-MM)₂MnBr₄ (2). Therefore, the structure was enriched with NLO, and its NLO can be switched by the structural phase transition. Then it is natural that the reversible dielectric switches were triggered in both the lead-free compounds by the phase changes. In addition, they exhibit bright green fluorescence under ultraviolet light, and the photoluminescence quantum efficiency reaches 47.24% and 40.69%, respectively. These results indicate that the halogen-modification strategy has injected new vitality into the exploration of the development of multi-response materials with NLO and dielectric switching performance.

中文翻译：

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卤素调节在具有绿色荧光的混合化合物中触发 NLO 和介电双开关

具有非线性光学（NLO）和介电双开关特性的混合金属卤化物是一类在光电子和智能设备领域具有巨大应用前景的材料。然而，有效地修改和调节分子结构以获得温度响应 NLO 开关性能仍然是一个挑战。在此，我们报告了一种通过使用卤素取代来改变对称性的策略。具有更大电负性的 Br 将对称性从中心对称 (Cl-MM) ₂ MnBr ₄ ( 1 ) 降低到非中心对称(Br-MM) ₂ MnBr ₄ ( 2 )）。因此，该结构富含 NLO，其 NLO 可以通过结构相变进行切换。然后很自然地，可逆介电开关在两种无铅化合物中都由相变触发。此外，它们在紫外光下呈现亮绿色荧光，光致发光量子效率分别达到47.24%和40.69%。这些结果表明，卤素改性策略为开发具有非线性光学和介电开关性能的多响应材料的探索注入了新的活力。