Excitonic landscape in 2D perovskites
Paulina Plochocka a
a Laboratoire National des Champs Magnétiques Intenses, CNRS, Avenue de Rangueil, 143, Toulouse, France
b Department of Experimental Physics, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
Proceedings of MATSUS Fall 2025 Conference (MATSUSFall25)
A1 Halide Perovskites - Properties, Synthesis and Advanced Characterization - #PeroProp
València, Spain, 2025 October 20th - 24th
Organizers: Kunal Datta and Selina Olthof
Invited Speaker, Paulina Plochocka, presentation 165
Publication date: 21st July 2025

High environmental stability and surprisingly high efficiency of solar cells based on 2D perovskites have renewed interest in these materials. These natural quantum wells consist of planes of metal-halide octahedra, separated by organic spacers. The unique synergy of soft lattice and opto-electronic properties are often invoked to explain superior characteristic of perovskites materials in applications. At the same time such unique synergy creates fascinating playground for exciton physics which challenges our understanding of this elementary excitation. I will demonstrate that even after decade of intense investigation the notation” unique” so often used in case of perovskites deserves serious scrutiny.

I will explore the excitonic landscape in 2D semiconductors. First, I will highlight the controversy surrounding the unexpectedly high light emission efficiency of this material and show that it can be explained by the interplay between phonons and the exciton fine structure. I will demonstrate that the soft lattice can suppress relaxation of excitons to dark state making 2D perovskites great light emitters. Moreover, I will discuss the exciton fine structure measured for multiple 2D layered perovskites characterized by a different lattice distortions imposed by organic spacers. Surprisingly, it has a non-trivial impact on the exchange interaction allowing the energy spacing between dark and bright excitons to be tuned. This tuning knob, not available in classic semiconductors, makes 2D perovskites a unique material system where the exciton manifold can be controlled via the steric effect. Finally, I will demonstrate alternative approach to the injection of spin-polarized carriers in 2D perovskites bu building Van der Waals heterostructures. 

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