Bonn 2025 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 70: Nanophotonics I

Q 70.1: Talk

Friday, March 14, 2025, 11:00–11:15, HS I PI

Exciton-Phonon Interactions at hBN/Perovskites Interfaces — •Sara Darbari^1,2, Masoud Taleb¹, Leon Multerer¹, Yaser Abdi¹, and Nahid Talebi¹ — ¹Institute for Experimental and Applied Physics, Christian Albrechts University in Kiel, Kiel, Germany — ²Electrical and Computer Engineering Faculty, Tarbiat Modares University, Tehran, Iran

2D perovskites have attracted significant interests due to their optical properties, especially high exciton binding energies at the room temperature. Despite higher stability in comparison with their 3D counterparts, 2D perovskites still suffer from photo-induced degradation that can be diminished by encapsulating them with other 2D materials like hexagonal boron nitride (hBN). hBN is a widegap and stable material, which is promising for quantum technologies owing to multiple classes of phonon-assisted quantum emitting defects. Here, we have transferred hBN on top of 2D Ruddlesden-Popper perovskite (RPP) flakes ((BA)2PbI4 with n=1), and investigated the hBN/RPP heterostructure by cathodoluminescence spectroscopy. Our results prove not only significantly retarded e-beam induced degradation of RPPs, but also an enhancement in the luminescent behavior at the excitonic wavelength of RPP and phonon sidebands. Furthermore, the excitonic peak bandwidth is reduced, coincident with a slight red shift. This sharp excitonic luminescent peak of hBN/RPP is detectable, when we excite the extruded parts of hBN, even micrometers away from the RPP edge. The observed behaviors are attributed to hBN phonons coupling to perovskite excitons in their heterostructure.

Keywords: 2D perovskite; hBN; exciton; phonon; cathodoluminescence