Addressing interface physics and related photoinduced dynamics is crucial to understand charge carrier paths and losses and ultimately design efficient optoelectronic devices. However, such dynamics are often masked when bulky systems are investigated. In this work, we combine photoluminescence with ultrafast transient absorption microscopy to map charge transfer processes in few-layers-thick heterostructures made of low-dimensional (C₆H₅CH₂CH₂NH₃)₂(CH₃NH₃)_n-1Pb_nI_3n+1 perovskite flakes of different dimensionalities (n = 3) and (n = 1). We observe that the hole transfer process from the (n = 3) to the (n = 1) phase happens after exciton diffusion on a time scale of tens of picoseconds, whereas electron transfer is hindered by the high exciton binding energy and low diffusion coefficient within the (n = 1) phase. This study sets the stage for a deeper understanding needed for the smart development of new heterostructure combinations with different dimensionalities and band alignments.

中文翻译：

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在低维卤化铅钙钛矿异质结构中对超快电荷转移进行成像


解决界面物理学和相关的光诱导动力学问题对于了解电荷载流子路径和损耗并最终设计高效的光电器件至关重要。然而，当研究大型系统时，这种动态往往被掩盖了。在这项工作中，我们将光致发光与超快瞬态吸收显微镜相结合，以绘制由低维 （C₆H₅CH₂CH₂NH₃）₂（CH₃NH₃）_n-1Pb_nI_3n+1 不同维度 （n = 3） 和 （n = 1） 钙钛矿薄片制成的几层厚异质结构中的电荷转移过程。我们观察到，从 （n = 3） 到 （n = 1） 相的空穴转移过程发生在激子扩散之后，时间尺度为数十皮秒，而电子转移受到 （n = 1） 相内高激子结合能和低扩散系数的阻碍。这项研究为更深入地理解具有不同维度和能带对齐的新异质结构组合的智能开发奠定了基础。