Department of Electrical and Computer Engineering, University of Toronto, 35 St. George Street, Toronto, ON, M5S 1A4, Canada.
CHESS Wilson Laboratory, Cornell University, 161 Synchrotron Drive, Ithaca, NY, 14853, USA.
Nat Commun. 2018 Oct 11;9(1):4214. doi: 10.1038/s41467-018-06746-5.
The quantum-confined Stark effect (QCSE) is an established optical modulation mechanism, yet top-performing modulators harnessing it rely on costly fabrication processes. Here, we present large modulation amplitudes for solution-processed layered hybrid perovskites and a modulation mechanism related to the orientational polarizability of dipolar cations confined within these self-assembled quantum wells. We report an anomalous (blue-shifting) QCSE for layers that contain methylammonium cations, in contrast with cesium-containing layers that show normal (red-shifting) behavior. We attribute the blue-shifts to an extraordinary diminution in the exciton binding energy that arises from an augmented separation of the electron and hole wavefunctions caused by the orientational response of the dipolar cations. The absorption coefficient changes, realized by either the red- or blue-shifts, are the strongest among solution-processed materials at room temperature and are comparable to those exhibited in the highest-performing epitaxial compound semiconductor heterostructures.
量子限制斯塔克效应（QCSE）是一种成熟的光学调制机制，但利用它实现的性能最佳的调制器依赖于昂贵的制造工艺。在这里，我们展示了溶液处理的层状混合钙钛矿的大调制幅度，以及与这些自组装量子阱中受限的偶极阳离子的取向极化率相关的调制机制。我们报告了包含甲铵阳离子的层的异常（蓝移）QCSE，而含有铯的层则表现出正常（红移）行为。我们将蓝移归因于激子结合能的非凡减小，这是由于偶极阳离子的取向响应导致电子和空穴波函数的分离增强引起的。通过红移或蓝移实现的吸收系数变化在室温下是溶液处理材料中最强的，可与表现最佳的外延化合物半导体异质结构中的变化相媲美。
