The development of multidimensional heterostructure (2D/3D) lead halide perovskites has emerged as an effective approach to enhancing the efficiency and long-term stability of perovskite solar cells (PSCs). However, a fundamental understanding of the working mechanisms, such as carrier extraction, and carrier transfer dynamics in the multidimensional perovskites heterostructures remains elusive. Here, we observe the ultrafast carrier extraction in highly efficient 2D/3D bilayer PSCs (power conversion efficiency of 21.12%) via femtosecond time-resolved pump–probe transient absorption spectroscopy (TAS). Notably, the formation of quasi-equilibrium states resulting in a subband absorption feature with an ultrafast lifetime of 440 fs was observed, and this feature is found only in 2D/3D perovskite heterostructure. The short-lived feature gives rise to the local electric-field-induced electroabsorption, resulting in an enhanced power conversion efficiency in 2D/3D PSCs. These findings can help comprehend the advanced working mechanism of highly efficient solar cells and other 2D/3D bilayer perovskite-based optoelectronic devices.

中文翻译：

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在高效 2D/3D 双层钙钛矿太阳能电池中揭示超快载流子提取

多维异质结构（2D/3D）卤化铅钙钛矿的发展已成为提高钙钛矿太阳能电池（PSC）效率和长期稳定性的有效方法。然而，对多维钙钛矿异质结构中载流子提取和载流子转移动力学等工作机制的基本理解仍然难以捉摸。在这里，我们通过飞秒时间分辨泵-探针瞬态吸收光谱 (TAS) 观察高效 2D/3D 双层 PSC 中的超快载流子提取（功率转换效率为 21.12%）。值得注意的是，观察到准平衡态的形成导致具有 440 fs 超快寿命的子带吸收特征，并且该特征仅在 2D/3D 钙钛矿异质结构中发现。这种短暂的特性会引起局部电场引起的电吸收，从而提高 2D/3D PSC 的功率转换效率。这些发现有助于理解高效太阳能电池和其他基于 2D/3D 双层钙钛矿的光电器件的先进工作机制。