Quantum-Assisted Photoelectric Effects in Perovskite Solar Cells

通过定制的尺寸工程生产的具有连续上移的价带的梯度2D钙钛矿帽壳可以有效地从3D钙钛矿核心中提取空穴。电子结构的实空间观测将充分揭示2D/3D混合钙钛矿太阳能电池（PSC）的工作机理。在本财政年度，光调制扫描隧道显微镜可视化了2D（C4 H9 NH3）2（CH 3 NH3）n-1 PbnI 3 n +1/3D CH 3 NH3 PbI 3堆叠钙钛矿的横截面能带排列。通过系统地分析它们的电子构型，可以在空间上分辨沿着垂直3D到2D方向的混合维钙钛矿能带结构。值得注意的是，2D钙钛矿中的电场在光照下比在黑暗条件下更大，导致分别分布在2D和3D钙钛矿中的空穴和电子的浓度增加。受益于这种电子重构，电荷复合被抑制，从而显著地提高了2D/3D PSC性能。此外，我们的方法开辟了一条途径，直接，本地映射的光电器件的能级。(Nano能源，2021，89，106362）

Graded 2D perovskite capping shells with continuously upshifting valence bands, produced by tailored dimensional engineering, can effectively extract holes from 3D perovskite cores. Real-space observation of electronic structures will fully reveal the operating mechanisms of 2D/3D hybrid perovskite solar cells (PSCs). In this financial year, the light-modulated scanning tunneling microscopy visualizes the cross-sectional band alignment across 2D (C4H9NH3)2(CH3NH3)n-1PbnI3n+1/3D CH3NH3PbI3 stacked perovskites. By systematically analyzing their electronic configuration, the mixed-dimensional perovskite band structure along the vertical 3D-to-2D direction can be spatially resolved. Remarkably, the electric field in the 2D perovskite is larger under light illumination than under dark conditions, resulting in an increase in the concentration of holes and electrons distributed in the 2D and 3D perovskites, respectively. Benefiting from this electronic reconstruction, charge recombination is suppressed, thereby significantly promoting the 2D/3D PSC performance. Moreover, our method opens an avenue for direct, local mapping of optoelectronic device energy levels. (Nano Energy, 2021, 89, 106362)