Establishing an effective interconnection between the crystal structure and photoelectric-related properties in layered materials is paramount for fostering efficient energy conversion. Here, we present a systematic demonstration of the adjustable and fascinating photoelectric properties alongside the intriguing molecular-ionic crystal transition in layered SbI under high pressure. With increasing pressure, the photocurrent response of SbI exhibits a dramatic enhancement, reaching a maximum of 100 mA/W at 4.4 GPa, which is nearly ten times the value (8 mA/W) at initial pressure, while maintaining an ultra-low dark current simultaneously. The substantial enhancement in photoelectric responses of SbI is intimately associated with the molecular to ionic isostructural phase transition, which is accompanied by an increase in coordination number and charge delocalization. Conversely, the crystal structure transition from hexagonal to monoclinic with a reduction in coordination number could cause a dramatic attenuation in photoelectric activities under higher pressure. These findings signify that the strong ionic crystal character, high coordination number and high charge delocalization would enormously contribute to photoelectric properties surge in layered metal halides, and this could potentially be extended to other layered functional materials to tune photoelectric-related properties.

中文翻译：

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高压下层状三碘化锑分子-离子晶体转变驱动的光电性能激增


在层状材料的晶体结构和光电相关特性之间建立有效的互连对于促进高效的能量转换至关重要。在这里，我们系统地展示了高压下层状 SbI 中可调节且令人着迷的光电特性以及有趣的分子-离子晶体转变。随着压力的增加，SbI的光电流响应表现出显着增强，在4.4 GPa下达到最大值100 mA/W，几乎是初始压力下值（8 mA/W）的十倍，同时保持超低暗电流同时电流。 SbI 光电响应的显着增强与分子到离子同构相变密切相关，这伴随着配位数和电荷离域的增加。相反，晶体结构从六方晶向单斜晶的转变以及配位数的减少可能会导致高压下光电活动的急剧衰减。这些发现表明，强离子晶体特性、高配位数和高电荷离域性将极大地促进层状金属卤化物光电性能的激增，并且这可能会扩展到其他层状功能材料以调整光电相关性能。