AI Article Synopsis
- The excitonic properties and band structure of atomically thin 2D perovskite crystals change significantly with thickness, allowing for new explorations in exciton physics.
- Researchers examined the fundamental excitonic characteristics, such as reduced mass and binding energy, in 2D perovskites using high magnetic field optical spectroscopy.
- Their findings challenge traditional ideas about quantum confinement, showing that the effective mass of carriers actually increases with the number of inorganic layers, indicating unique design potential for electronic properties in 2D perovskites.
Article Abstract
In atomically thin two-dimensional (2D) crystals, the excitonic properties and band structure scale strongly with the thickness, providing a new playground for the investigation of exciton physics in the ultimate confinement regime. Here, we demonstrate the evolution of the fundamental excitonic properties, such as reduced mass, wave function extension, and exciton binding energy, in the 2D perovskite (PEA)(MA)PbI, for = 1, 2, 3. These parameters are experimentally determined using optical spectroscopy in a high magnetic field up to 65 T. The observation of the interband Landau level transitions provides direct access to the reduced effective mass μ and band gap . We show that μ increases with the number of inorganic sheets , reaching the value of three-dimensional (3D) MAPbI already for = 3. Our experimental observations contradict the general expectation that quantum confinement leads to an enhanced carrier mass, showing another aspect of the unprecedented flexibility in the design of the electronic properties of 2D perovskites.
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