Exciton-polariton quasi-particles in 2D Ruddlesden-Popper perovskites explored by complementary all-optical and electron-beam spectroscopy

• Applicant: Professorin Nahid Talebi, Ph.D.
• Subject Area: Experimental Condensed Matter Physics ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 554905035

Van der Waals materials have emerged as a platform for novel functionalities, spanning me-chanical, electronic, and optoelectronic properties. Quasi-particle interactions in these materi-als and hybrid systems are extensively explored due to novel quantum correlations, quantum optical properties, and strong light-matter interactions. Our proposal aims to optimize the ma-terial properties of perovskites and examine their optical properties for strong coupling effects of excitons to photons. Specifically, we seek to develop a stable, high-quality two-dimensional Ruddlesden-Popper Perovskite (RPP) system with tunable exciton energies and explore exciton-polaritons in RPP coupled to high-quality plasmonic cavities and photonic crystal structures, using advanced characterization techniques like deep sub-wavelength ca-thodoluminescence spectroscopy. Our goal is to tailor the photophysics of perovskites by cou-pling with photonics and plasmonic cavities to enable superradiance and superfluorescence effects. We will use a systematic and controlled synthesis approach to create highly stable RPP crys-tals, followed by mechanical exfoliation and encapsulation. We will explore various molecu-lar systems as barriers and control the crystalline forms to achieve specific exciton energies at room temperature. The synthesized RPPs will be combined with precisely designed plasmonic cavities and crystals to (i) enhance coupling to photons using photonic modes in void plas-monic structures; (ii) explore exciton-plasmon interaction; and (iii) actively control the band structure of plasmonic crystals using strong exciton-plasmon interactions. For these purposes, we will use a combination of optical techniques, including photoluminescence spectroscopy, reflection and transmission spectroscopy, and cathodoluminescence spectroscopy in a scan-ning electron microscope. Our proposal involves synergistic efforts in materials synthesis, plasmonics, and nanooptics. Initially, we will systematically explore factors leading to the synthesis of stable and high-quality RPPs. Next, we aim to address key questions concerning the interactions between pho-tons and excitons in RPPs. We will measure the dispersion of exciton polaritons using linear optical spectroscopy techniques and visualize their propagation dynamics and length using deep-sub-wavelength characterization techniques. Additionally, we will examine the dephas-ing time of exciton polaritons, focusing on the roles of propagation loss and radiation decay in ultrafast dephasing dynamics. Our work will significantly impact the field of exciton polari-tons and strong coupling effects, as well as the optoelectronic applications of perovskites.

• DFG Programme: Research Grants
• International Connection: Iran
• Cooperation Partner: Professorin Dr. Sara Darbari