Bouduban Marine E F, Queloz Valentin I E, Caselli Valentina M, Cho Kyung Taek, Kirmani Ahmad R, Paek Sanghyun, Roldan-Carmona Cristina, Richter Lee J, Moser Jacques E, Savenije Tom J, Nazeeruddin Mohammad Khaja, Grancini Giulia
Photochemical Dynamics Group , Institute of Chemical Sciences and Engineering, EPFL , Station 6 , CH-1015 Lausanne , Switzerland.
Group for Molecular Engineering of Functional Materials , Institute of Chemical Sciences and Engineering, EPFL , Valais Wallis, Rue de l'Industrie 17 , CH-1951 Sion , Switzerland.
J Phys Chem Lett. 2019 Oct 3;10(19):5713-5720. doi: 10.1021/acs.jpclett.9b02224. Epub 2019 Sep 12.
Combining halide perovskites with tailored dimensionality into two/three-dimensional (2D/3D) systems has revealed a powerful strategy to boost the performances of perovskite photovoltaics (PVs). Despite recent advances, a clear understanding of the intimate link between interface structure and physics is still missing, leading so far to a blind optimization of the 2D/3D PVs. Here, we reveal the impact of 2D/3D crystal alignment in driving interface charge-recombination dynamics. The 2D crystal growth and orientation are manipulated by specific fluorination of phenethylammonium (PEA), used here as the organic cation backbone of the 2D component. By means of time-resolved optoelectronic analysis from the femto- to microsecond regions, we demonstrate a static function of the 2D layer as an electron barrier and homogeneous surface passivant, together with a dynamic role in retarding back charge recombination. Our results reveal a crucial dependence of such beneficial effects with the 2D layer, leading to an enhanced open-circuit voltage (), mostly attributed to the 2D phase which orients parallel on the 3D layer. Such findings provide a deep understanding and delineate precise guidelines for the smart design of multidimensional perovskite interfaces for advanced PVs and beyond.
将具有定制维度的卤化物钙钛矿组合成二维/三维（2D/3D）系统，已揭示出一种提高钙钛矿光伏（PV）性能的有效策略。尽管最近取得了进展，但对界面结构与物理之间紧密联系的清晰理解仍然缺失，这导致到目前为止对2D/3D PV进行盲目优化。在此，我们揭示了2D/3D晶体排列在驱动界面电荷复合动力学方面的影响。二维晶体的生长和取向通过苯乙铵（PEA）的特定氟化来控制，这里PEA用作二维组分的有机阳离子主链。通过从飞秒到微秒区域的时间分辨光电分析，我们证明了二维层作为电子阻挡层和均匀表面钝化剂的静态功能，以及在阻碍反向电荷复合方面的动态作用。我们的结果揭示了这种有益效果对二维层的关键依赖性，导致开路电压（）提高，这主要归因于在三维层上平行取向的二维相。这些发现为先进光伏及其他领域的多维钙钛矿界面的智能设计提供了深入理解并划定了精确指导方针。
