Magnetism in a 2D Hybrid Ruddlesden–Popper Perovskite through Charge Redistribution Driven by an Organic Functional Spacer

Abstract

Two-dimensional Ruddlesden–Popper (RP) perovskites are emerging materials offering great synthetic versatility and remarkable features due to the tunability of their crystal structure. We present a novel strategy to provide magnetism in a 2D RP perovskite using histidine molecules as a spacer, which could induce charge rebalancing at the interface of the inorganic layer. We observe that the amide and imidazole groups are close to Pb ions. The interaction with the imidazole indicates that this functional group, possibly assisted by the carboxyl close to the vicinity of the amine terminal, is inducing charge rearrangement from Pb2+ to paramagnetic Pb3+ ions, resulting in a positive magnetic moment. This magnetized 2D hybrid perovskites can be classified as a novel class of promising materials showing a magnetic moment at their interface, which may result in intriguing physical properties due to a delicate balance between magnetism and a quantum well confinement effect in the inorganic layer.

Atomistic Description of the Impact of Spacer Selection on Two-Dimensional (2D) Perovskites: A Case Study of 2D Ruddlesden–Popper CsPbI3 Analogues

“…The role played by the organic A′ spacing cations that separate, both spatially and electronically, adjacent inorganic layers in 2DPKs is largely dependent on their size, orientation, mutual interactions between spacers, and organic–inorganic interactions at the spacer–perovskite interface. − These A′ cations come with a broad range of chemical diversity. In the study presented here, ThMA and ThFA are representative of monoammonium and diammonium aromatic spacing cations, respectively, with the aromatic portion consisting of a thiophene heterocycle, and the pFBA spacer is a monoammonium aromatic spacer with a para -substituted fluorine atom on the benzene ring.…”

Biomolecules incorporated in halide perovskite nanocrystals: synthesis, optical properties, and applications

“…3c). 85 The layered nature of RP perovskites relies on the use of a bifunctional spacer molecule, as discussed in section 3. The amount of His determined the number of layers, and notably this is the first instance reported of the imidazole from His successfully coordinating to Pb 2+ in a HP.…”

“…The coordination of His with the lead ions was also observed to locally generate Pb 3+ instead of Pb 2+ at the interface, which induced magnetic properties in the material. 85…”

Chiral 2D organic–inorganic hybrid perovskites based on l-histidine

“…It was proposed that the imidazole group, possibly assisted by the carboxyl group close to the vicinity of the terminal amine, is provoking charge rearrangement from Pb 2+ to paramagnetic Pb 3+ ions, resulting in a positive magnetic moment. 55 According to all aforementioned achievements, histidinebased hybrid perovskites may be promising for various applications including photovoltaics, optoelectronics, spintronics etc. Unfortunately, the field of hybrid perovskites incorporating histidine molecules is still not explored.…”

“…It was proposed that the imidazole group, possibly assisted by the carboxyl group close to the vicinity of the terminal amine, is provoking charge rearrangement from Pb 2+ to paramagnetic Pb 3+ ions, resulting in a positive magnetic moment. 55…”