Perovskite materials with tunable electronic and structural characteristics can realize various physical properties including electrical/ionic conduction, ferroelectricity, and luminescence. Integrating and coupling these properties in a single perovskite material offer new possibilities for fundamental research and applications. In particular, coupling ferroelectricity and luminescence would enable novel applications. Here, we report that the metal-free ferroelectric perovskite MDABCO ( N -methyl- N ′-diazabicyclo[2.2.2]octonium)–ammonium triiodide exhibits coupled superior ferroelectricity and visible photoluminescence (PL). Besides strong second-harmonic generation (SHG) associated with its ferroelectricity, MDABCO–ammonium triiodide shows long-lifetime PL at room temperature. Remarkably, the PL intensity depends strongly on the polarization of the excitation light. We found that this anisotropy is coupled to the local crystal orientation that was determined by polarization-resolved SHG. Our results suggest that the anisotropic PL property can be tuned in response to its ferroelectric state via an external field and, thereby, presents a previosuly unobserved functionality in perovskites.

中文翻译：

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无金属铁电卤化物钙钛矿表现出与局部铁电相关的可见光致发光

具有可调电子和结构特性的钙钛矿材料可以实现各种物理特性，包括电/离子传导、铁电和发光。在单一钙钛矿材料中集成和耦合这些特性为基础研究和应用提供了新的可能性。特别是，耦合铁电性和发光将实现新的应用。在这里，我们报告了无金属铁电钙钛矿 MDABCO (ñ-甲基-ñ'-二氮杂双环[2.2.2]辛鎓）-三碘化铵表现出优异的铁电性和可见光致发光（PL）。除了与其铁电性相关的强二次谐波产生（SHG）外，MDABCO-三碘化铵在室温下表现出长寿命的 PL。值得注意的是，PL 强度很大程度上取决于激发光的偏振。我们发现这种各向异性与由偏振分辨 SHG 确定的局部晶体取向有关。我们的结果表明，各向异性的 PL 特性可以通过外部场响应其铁电状态进行调整，从而在钙钛矿中呈现出以前未观察到的功能。