Wang Hengshan, Bao Yanan, Li Jing, Li Dongwen, An Meiqi, Tang Lingzhi, Li Jianliang, Tang Huayi, Chi Yaodan, Xu Jiao, Yang Yiming
School of Microelectronics, Dalian University of Technology, No. 321 Tuqiang Road, Dalian 116620, China.
Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Physics, Dalian University of Technology, No. 2 Linggong Road, Dalian 116024, China.
J Phys Chem Lett. 2023 Nov 9;14(44):9943-9950. doi: 10.1021/acs.jpclett.3c02394. Epub 2023 Oct 30.
The coupled ionic and electronic transport in halide perovskites opens up new possibilities for semiconductor iontronic devices beyond solar cells. Nevertheless, the fundamental understanding of ionic behavior at the microscale remains vague, largely because of the inhomogeneity in polycrystalline thin films. Here, we show that the ion dynamics in single-crystalline perovskite nanoplates (NPs) are significantly different and that an external bias may induce highly anisotropic ionic transport in the NPs, thereby leading to a greatly enhanced local electric field. Using modified scanning photocurrent microscopy (SPCM), the origin of the photocurrent is pinpointed to the cathode region of the NP device, where subsequent energy dispersive spectroscopy (EDS) characterization confirms a large accumulation of halogen vacancies. In addition, the Kelvin probe force microscopy (KPFM) measurement demonstrates a strong built-in electric field within a submicron length near the cathode, which alters the local electronic structure for efficient photo carrier separation. Such field-induced ionic behavior deepens the understanding of ion dynamics in perovskites and promotes scale-down of perovskite micro- and nanoiontronic and ion-optoelectronic devices.
卤化物钙钛矿中的离子与电子耦合输运为超越太阳能电池的半导体离子电子器件开辟了新的可能性。然而，由于多晶薄膜的不均匀性，对微观尺度下离子行为的基本理解仍然模糊不清。在此，我们表明单晶钙钛矿纳米板（NP）中的离子动力学显著不同，并且外部偏压可能会在NP中诱导高度各向异性的离子输运，从而导致局部电场大大增强。通过改进的扫描光电流显微镜（SPCM），将光电流的起源定位到NP器件的阴极区域，随后的能量色散光谱（EDS）表征证实了大量卤素空位的积累。此外，开尔文探针力显微镜（KPFM）测量表明在阴极附近的亚微米长度范围内存在强内建电场，这改变了局部电子结构以实现有效的光载流子分离。这种场诱导的离子行为加深了对钙钛矿中离子动力学的理解，并促进了钙钛矿微纳离子电子器件和离子光电器件的小型化。
