Lu Haipeng, Xiao Chuanxiao, Song Ruyi, Li Tianyang, Maughan Annalise E, Levin Andrew, Brunecky Roman, Berry Joseph J, Mitzi David B, Blum Volker, Beard Matthew C
Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
Department of Mechanical Engineering and Material Science, Duke University, Durham, North Carolina 27708, United States.
J Am Chem Soc. 2020 Jul 29;142(30):13030-13040. doi: 10.1021/jacs.0c03899. Epub 2020 Jul 16.
Incorporating chiral organic molecules into organic/inorganic hybrid 2D metal-halide perovskites results in a novel family of chiral hybrid semiconductors with unique spin-dependent properties. The embedded chiral organic moieties induce a chiroptical response from the inorganic metal-halide sublattice. However, the structural interplay between the chiral organic molecules and the inorganic sublattice, as well as their synergic effect on the resulting electronic band structure need to be explored in a broader material scope. Here we present three new layered tin iodide perovskites templated by chiral (/-)methylbenzylammonium (-MBA), i.e., (-/-MBA)SnI, and their racemic phase (-MBA)SnI. These MBASnI compounds exhibit the largest level of octahedral bond distortion compared to any other reported layered tin iodide perovskite. The incorporation of chiral MBA cations leads to circularly polarized absorption from the inorganic Sn-I sublattice, displaying chiroptical activity in the 300-500 nm wavelength range. The bandgap and chiroptical activity are modulated by alloying Sn with Pb, in the series of (MBA)PbSnI. Finally, we show that vertical charge transport through oriented (-/-MBA)SnI thin films is highly spin-dependent, arising from a chiral-induced spin selectivity (CISS) effect. We demonstrate a spin-polarization in the current-voltage characteristics as high as 94%. Our work shows the tremendous potential of these chiral hybrid semiconductors for controlling both spin and charge degrees of freedom.
将手性有机分子引入有机/无机杂化二维金属卤化物钙钛矿中，可形成一类具有独特自旋相关特性的新型手性杂化半导体。嵌入的手性有机部分会引发无机金属卤化物亚晶格的手性光学响应。然而，手性有机分子与无机亚晶格之间的结构相互作用，以及它们对所得电子能带结构的协同效应，需要在更广泛的材料范围内进行探索。在此，我们展示了三种由手性（±）-甲基苄基铵（±MBA）模板化的新型层状碘化锡钙钛矿，即（±MBA）SnI₄，以及它们的外消旋相（±MBA）₂SnI₆。与其他已报道的层状碘化锡钙钛矿相比，这些MBASnI化合物表现出最大程度的八面体键畸变。手性MBA阳离子的引入导致无机Sn-I亚晶格产生圆偏振吸收，在300 - 500 nm波长范围内显示出手性光学活性。在（MBA）PbₓSn₁₋ₓI₄系列中，通过将Sn与Pb合金化来调节带隙和手性光学活性。最后，我们表明，通过取向的（±MBA）SnI₄薄膜的垂直电荷传输高度依赖于自旋，这是由手性诱导自旋选择性（CISS）效应引起的。我们在电流-电压特性中展示了高达94%的自旋极化。我们的工作表明，这些手性杂化半导体在控制自旋和电荷自由度方面具有巨大潜力。
