SKM 2023 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 1: 2D Materials and their Heterostructures I: Graphene
DS 1.6: Vortrag
Montag, 27. März 2023, 10:45–11:00, SCH A 316
Mobile trions in two-dimensional hybrid perovskites — Jonas David Ziegler1, Yeongsu Cho2, •Sophia Terres1, Matan Menahem3, Omer Yaffe3, Takashi Taniguchi4, Kenji Watanabe4, Timothy C. Berkelbach2, and Alexey Chernikov1 — 1TU Dresden, Dresden, Deutschland — 2Columbia University, New York, USA — 3Weizmann Institute of Science, Rehovot, Israel — 4National Institute for Materials Science, Tsukuba, Japan
Two-dimensional hybrid perovskites represent natural quantum well systems composed of alternating organic and inorganic molecular layers. They combine an efficient coupling of electrons to a soft lattice with strong Coulomb interactions between the charge carriers. The latter leads to the formation of tightly bound excitons that determine the optical response of this class of materials. The interaction between excitons and free charge carriers, however, remains difficult to access in halide perovskites due to persistent challenges to introduce doping.
Here, we report experimental realization of electrically tunable, ultrathin two-dimensional perovskites, by combining them with hBN and multilayer graphene in field-effect transistor geometries. We demonstrate the formation of both negatively and positively charged exciton-electron complexes, known as trions with binding energies up to 46 meV. These values are a direct consequence of strong Coulomb interaction and scale with exciton binding energies, as demonstrated by theoretical calculations. The trions exhibit finite oscillator strength in absorption-like response, are localized at cryogenic temperatures, and exhibit thermally activated diffusion at 50 K.