平面Ag/MAPbI₃薄单晶器件中的光可调阈值开关与热激活输运
Optically Tunable Threshold Switching and Thermally Activated Transport in Planar Ag/MAPbI$_3$ Thin Single-Crystal Devices
AI总结：
该研究制备了Ag/MAPbI₃平面单晶器件，发现其具有超低暗电流，光照下出现阈值开关和极性滞回，揭示了Ag/钙钛矿界面耦合离子过程的输运机制。
AI中文摘要：
卤化物钙钛矿已在光电子学领域取得重大进展，应用范围远超光伏领域。其混合离子-电子传导曾被认为不利于器件稳定性，如今却日益被视为存储和类神经形态器件的功能自由度，尤其在与光等外部刺激耦合时。单晶是极具吸引力的模型，因为它们能抑制多晶薄膜中掩盖本征输运和界面机制的晶界效应与微结构无序。本研究通过限域法生长了薄甲胺铅碘（MAPbI₃）单晶，并将其集成到具有直接沉积Ag电极的平面两端器件中。室温下，该器件表现出超低暗电流（10⁻¹³-10⁻¹² A），且在黑暗中几乎无滞回特性。光照下，电流因光生载流子产生而增加，I-V特性出现明显的极性相关滞回以及两种电导态之间类阈值的转变。300-400 K的变温暗测量显示，输运受热激发和电极影响，归一化滞回度量变化微弱。结合背对背肖特基二极管分析以及使用更惰性电极材料的对照器件，这些结果支持一种输运模型：Ag/钙钛矿界面起核心作用，且滞回响应对受耦合的界面和离子过程影响。
英文摘要：
Halide perovskites have enabled major advances in optoelectronics, extending well beyond photovoltaics. Their mixed ionic-electronic conduction, once regarded as detrimental to device stability, is increasingly viewed as a functional degree of freedom for memory and neuromorphic-inspired devices, especially when coupled to external stimuli such as light. Specifically, single crystals are attractive models because they suppress grain-boundary effects and microstructural disorder that can mask intrinsic transport and interfacial mechanisms in polycrystalline films. Here, we report the growth of thin methylammonium lead iodide (MAPbI$_3$) single crystals by a space-confined method and their integration into planar two-terminal devices with directly deposited Ag contacts. At room temperature, the devices exhibit ultra-low dark currents ($10^{-13}-10^{-12}$ A) and negligible hysteresis in the dark. Under illumination, the current increases due to photogeneration and the I-V characteristics develop a pronounced polarity-dependent hysteresis and a threshold-like transition between two conductance states. Temperature-dependent dark measurements (300-400 K) show thermionically activated, contact-influenced transport and a weakly varying normalized hysteresis metric. Together with the back-to-back Schottky-diode analysis and control devices using more inert contact materials, these results support a transport model in which Ag/perovskite interfaces play a central role and the hysteretic response is influenced by coupled interfacial and ionic processes.
