Dyksik Mateusz, Wang Shuli, Paritmongkol Watcharaphol, Maude Duncan K, Tisdale William A, Baranowski Michal, Plochocka Paulina
Laboratoire National des Champs Magnétiques Intenses, UPR 3228, CNRS-UGA-UPS-INSA, Grenoble and Toulouse, France.
Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland.
J Phys Chem Lett. 2021 Feb 18;12(6):1638-1643. doi: 10.1021/acs.jpclett.0c03731. Epub 2021 Feb 8.
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.
在原子级薄的二维（2D）晶体中，激子特性和能带结构与厚度密切相关，为在极限限制条件下研究激子物理提供了一个新的平台。在此，我们展示了二维钙钛矿（PEA）（MA）PbI₃中，对于n = 1、2、3时，基本激子特性（如折合质量、波函数扩展和激子结合能）的演变。这些参数是通过在高达65 T的强磁场中使用光谱学实验测定的。带间朗道能级跃迁的观测提供了直接获取折合有效质量μ和带隙Eg的途径。我们表明，μ随着无机层数n的增加而增大，对于n = 3时已经达到三维（3D）MAPbI₃的值。我们的实验观测结果与量子限制导致载流子质量增加的一般预期相矛盾，这展示了二维钙钛矿电子特性设计中前所未有的灵活性的另一个方面。
