• Divitini, Giorgio
• Krahne, Roman
• Schleusener, Alexander
• Faraji, Mehrdad
• Lauciello, Simone
• Abkenar, Sirous Khabbaz
• Borreani, Martina
• Pasquale, Lea

Abstract

<jats:title>Abstract</jats:title><jats:p>Layered perovskites consist of stacks of inorganic semiconducting metal halide octahedra lattices sandwiched between organic layers with typically dielectric behavior. The in‐plane confinement of electrical carriers in such two‐dimensional metal halide perovskites drives a large range of appealing electronic properties, such as strong exciton binding, anisotropic charge diffusion, and directionality in polarization. Heterostructures can provide additional control on charge carrier diffusion and localization, and in‐plane heterojunctions are particularly attractive because of the high charge mobility in this direction. Here, we demonstrate a versatile solution‐based approach to fabricate in‐plane heterostructures with different halide composition in two‐dimesional lead‐halide perovskite microscrystals. The exchange reaction leads to spatially separated halide phases with different band gap and light emission. The exposure of microcrystals to different halide salts in solution leads to a core‐shell heterostructure architecture. Interestingly, the composition of the exchanged phase and the morphology of the phase boundary depends on the exchange route. For Br to I we observe a rugged boundary and a relatively pure exchanged crystal phase, while I to Br leads to alloyed phases in the exchanged region and a smooth interface. The different reaction mechanisms can be related to the preferred localisation of the halides at the equatorial or axial octahedra positions that either leads to dissolution and recrystallization of the octahedra lattice, or allows for ion diffusion within the lattice. These detailed insights on the ion exchange processes in layered perovskites will stimulate the development of heterostructures that can be tailored for different applications such as photocatalysis, energy storage, and light emission.</jats:p><jats:p>This article is protected by copyright. All rights reserved</jats:p>

Topics

• perovskite
• impedance spectroscopy
• phase
• mobility
• anisotropic
• layered
• recrystallization
• phase boundary