Schmitt Tanja, Bourelle Sean, Tye Nathaniel, Soavi Giancarlo, Bond Andrew D, Feldmann Sascha, Traore Boubacar, Katan Claudine, Even Jacky, Dutton Siân E, Deschler Felix
Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
Cambridge Graphene Centre, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom.
J Am Chem Soc. 2020 Mar 18;142(11):5060-5067. doi: 10.1021/jacs.9b11809. Epub 2020 Mar 6.
Layered hybrid metal-halide perovskites with non-centrosymmetric crystal structure are predicted to show spin-selective band splitting from Rashba effects. Thus, fabrication of metal-halide perovskites with defined crystal symmetry is desired to control the spin-splitting in their electronic states. Here, we report the influence of halogen -substituents on the crystal structure of benzylammonium lead iodide perovskites (4-CHCHNH)PbI ( = H, F, Cl, Br). Using X-ray diffraction and second-harmonic generation, we study structure and symmetry of single-crystal and thin-film samples. We report that introduction of a halogen atom lowers the crystal symmetry such that the chlorine- and bromine-substituted structures are non-centrosymmetric. The differences can be attributed to the nature of the intermolecular interactions between the organic molecules. We calculate electronic band structures and find good control of Rashba splittings. Our results present a facile approach to tailor hybrid layered metal halide perovskites with potential for spintronic and nonlinear optical applications.
具有非中心对称晶体结构的层状混合金属卤化物钙钛矿预计会因 Rashba 效应而呈现自旋选择性能带分裂。因此，需要制备具有特定晶体对称性的金属卤化物钙钛矿来控制其电子态中的自旋分裂。在此，我们报告了卤素取代基对苄基碘化铅钙钛矿（4-CHCHNH）PbI（ = H、F、Cl、Br）晶体结构的影响。利用 X 射线衍射和二次谐波产生，我们研究了单晶和薄膜样品的结构与对称性。我们报告称，引入卤素原子会降低晶体对称性，使得氯取代和溴取代的结构为非中心对称。这些差异可归因于有机分子间分子间相互作用的性质。我们计算了电子能带结构并发现对 Rashba 分裂有良好的控制。我们的结果提出了一种简便方法来定制具有自旋电子学和非线性光学应用潜力的混合层状金属卤化物钙钛矿。
