Sequential Recrystallization for the Design of Two-Dimensional Layered Perovskite Heterostructures

Mehrdad Faraji^a^,^b, Alexander Schleusener^a, Roman Krahne^a

^aItalian Institute of Technology (IIT), Via Morego 30, 16163 Genoa, Italy

^bDipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, Via Dodecaneso, 31, Genova 16146, Italy

Proceedings of Emerging Light Emitting Materials 2026 (EMLEM26)

Kallithea, Greece, 2026 September 20th - 23rd

Organizers: Grigorios Itskos and Maksym Kovalenko

Oral, Alexander Schleusener, presentation 017
Publication date: 8th July 2026

The local energy landscape in semiconductors is essential for controlling charge-carrier and exciton transport in optoelectronic devices.[1] In two-dimensional metal halide perovskites (2DLPs), semiconducting metal-halide layers are separated by bulky organic spacer cations that largely suppress out-of-plane transport, making vertical heterostructures less effective for engineering charge and energy flow.[2] In contrast, lateral heterojunctions enable in-plane control of composition while preserving efficient transport within the inorganic framework, thereby providing an attractive platform for band-gap engineering. However, general synthetic strategies for the deterministic fabrication of such heterostructures remain elusive.

Here, we introduce a versatile one-pot sequential recrystallization strategy for fabricating lateral 2DLP heterostructures.[3] The method exploits differences in solubility and crystallization kinetics, while the sequence, timing, and composition of precursor injections determine the resulting heterostructure architecture. This approach enables the formation of heterojunctions between materials with different halides and metal cations and can be extended to multiple heterojunctions incorporating up to three different halides. Furthermore, we identify two distinct heterostructure morphologies, core-frame and triptych-shaped, that arise from different crystallographic orientations of the core crystal, leading to facet-selective growth of the surrounding phase. The resulting heterostructures exhibit crystalline junctions, tunable multicolour emission, and optical and electronic coupling across the interfaces. Beyond demonstrating a broad range of heterostructure architectures in 2DLPs, this sequential recrystallization strategy has the potential to provide a general route for band-gap engineering in solution-processable low-dimensional semiconductors.

References:

[1] Tatarinov, D. A., Schleusener, A. & Krahne, R. Controlling Energy Flow in Perovskite Heterostructures Through Dimensionality and Phase Engineering. Advanced Science 12, e05971 (2025).

[2] Li, X.; Hoffman, J. M.; Kanatzidis, M. G. The 2D Halide Perovskite Rulebook: How the Spacer Influences Everything from the Structure to Optoelectronic Device Efficiency. Chem. Rev. 2021, 121 (4), 2230–2291]

[3] Faraji, M. et al. Heterostructure Design in Two-Dimensional Perovskites by Sequential Recrystallization. Preprint at https://doi.org/10.48550/arXiv.2512.13299 (2025).

Acknowledgements:

A. S. acknowledges the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Funding Program (Project Together, grant agreement No.101067869).

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