Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 45: Perovskite and Photovoltaics: Spectroscopy

HL 45.6: Vortrag

Donnerstag, 12. März 2026, 16:30–16:45, POT/0006

Intra- and Interlayer Excitonic Finestructure of (PEA)₂PbI₄ — •Patrick Grenzer¹, Fabian Lie², Klaus H. Eckstein¹, Linn Leppert², and Tobias Hertel¹ — ¹Institute of Physical and Theoretical Chemistry, Julius-Maximilians-University Würzburg, Germany — ²MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands

Layered halide perovskites exhibit strongly bound excitons shaped by reduced dimensionality, dielectric confinement, and significant spinorbit coupling. Despite extensive work, the origin of the multiple resonances in absorption and PL of (PEA)₂PbI₄ remains subject to debate. We investigate the excitonic fine structure in high-quality, mechanically exfoliated single crystals by combining temperature- and polarization-resolved photoluminescence with first-principles GW+BSE calculations. The polarization dependence unambiguously assigns the observed features to distinct excitonic states and resolves the contributions from exchange interactions, crystal symmetry, and interlayer coupling. We further identify and spectroscopically separate intra- and interlayer excitons and their respective transition dipole moments. The results provide a consistent microscopic picture of the exciton manifold in (PEA)₂PbI₄ and clarify the origins of the multi-line structure characteristic of this material class.

Keywords: 2D halide perovskites; Exciton fine structure; Polarization-resolved photoluminescence; GW–BSE calculations; Intra- and interlayer excitons