Proceedings of MATSUS Spring 2025 Conference (MATSUSSpring25)
DOI: https://doi.org/10.29363/nanoge.matsusspring.2025.604
Publication date: 16th December 2024
Title: Exciton in Halide Perovskite Nanoplatelets: Finite Confinement and Dielectric Effect in Effective Mass Approximation
Kaouther Tlili,†,‡ (Presenting author) Maria Chamarro,‡ Kais Boujdaria,† and Christophe Testelin ‡
†Université de Carthage, Faculté des Sciences de Bizerte, LR01ES15 Laboratoire de Physique des Matériaux : Structure et Propriétés, 7021 Zarzouna, Bizerte, Tunisia.
‡Sorbonne Université, CNRS, Institut des NanoSciences de Paris, F-75005, Paris, France.
Two-dimensional (2D) lead halide perovskite (LHP) nanoplatelets (NPLs) have garnered significant interest due to their exceptional optoelectronic properties, such as high exciton binding energy, narrow emission lines, and robust room-temperature excitonic stability. These features make them promising candidates for advanced photonic and optoelectronic applications [1], including light-emitting diodes [2], solar cells [3], and photodetectors [4]. Predicting and controlling excitonic properties in these systems is critical for their integration into practical devices.
In this study, we investigate the excitonic properties of CsPbBr3 and CsPbI3 NPLs using an advanced effective mass approximation (EMA) framework. The model incorporates quantum and dielectric confinements, finite potential barriers, and thickness-dependent carrier masses. Additionally, we explore the dependence of Bloch functions on the NPL width, enabling a detailed understanding of how lattice distortions and confinement modulate the electronic states near the band edges. This refined approach addresses the limitations of infinite-confinement models [5,6,7,8] and provides a realistic description of the excitonic behaviour in nanoscale systems.
Our results reveal a strong influence of dielectric contrast and quantum confinement on excitonic energy and binding energy. For thin NPLs, we achieve good agreement with experimental data [9,10], particularly when finite potential barriers and variable effective masses are included. The model demonstrates a significant enhancement in exciton binding energies due to dielectric effects and quantum confinement. Incorporating Bloch function dependence on NPL width further refines the description of excitonic fine structures, revealing critical interactions between carrier delocalization, dielectric mismatches, and finite potential offsets at interfaces.
This work establishes a robust theoretical framework for understanding and predicting the excitonic properties of LHP NPLs. The findings underscore the influence of the ligand environment and its importance on dielectric and finite confinement effects in achieving precise control over excitonic behaviour in quasi-two-dimensional materials.
References:
[1] Li, H. et al. (2021). Energy & environmental materials, 4(1), 46-64.
[2] Gan, X et al. (2017). 2D. Solar Energy Materials and Solar Cells, 162, 93-102.
[3] Cui, J et al. (2021). Science Advances, 7(41), eabg8458.
[4] Liu, X et al. (2017). Small, 13(25), 1700364.
[5] Ghribi, A. et al. (2021).. Nanomaterials, 11(11), 3054.
[6] Rajadell et al. (2017). Physical Review B, 96(3), 035307.
[7] Movilla et al. (2023). Nanoscale Advances, 5(22), 6093-6101.
[8] Gramlich, M et al. (2022). Advanced Science, 9(5), 2103013.
[9] Bohn, B. J et al. (2018). Nano letters, 18(8), 5231-5238.
[10] Wang, S et al. (2022).
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