Kumar Abhishek, Solanki Ankur, Manjappa Manukumara, Ramesh Sankaran, Srivastava Yogesh Kumar, Agarwal Piyush, Sum Tze Chien, Singh Ranjan
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
Center for Disruptive Photonic Technologies, The Photonics Institute, 50 Nanyang Avenue, Nanyang Technological University, Singapore 639798, Singapore.
Sci Adv. 2020 Feb 21;6(8):eaax8821. doi: 10.1126/sciadv.aax8821. eCollection 2020 Feb.
In recent years, two-dimensional (2D) Ruddlesden-Popper perovskites have emerged as promising candidates for environmentally stable solar cells, highly efficient light-emitting diodes, and resistive memory devices. The remarkable existence of self-assembled quantum well (QW) structures in solution-processed 2D perovskites offers a diverse range of optoelectronic properties, which remain largely unexplored. Here, we experimentally observe ultrafast relaxation of free carriers in 20 ps due to the quantum confinement of free carriers in a self-assembled QW structures that form excitons. Furthermore, hybridizing the 2D perovskites with metamaterials on a rigid and a flexible substrate enables modulation of terahertz fields at 50-GHz modulating speed, which is the fastest for a solution-processed semiconductor-based photonic device. Hence, an exciton-based ultrafast response of 2D perovskites opens up large avenues for a wide range of scalable dynamic photonic devices with potential applications in flexible photonics, ultrafast wavefront control, and short-range wireless terahertz communications.
近年来，二维（2D）Ruddlesden-Popper钙钛矿已成为环境稳定型太阳能电池、高效发光二极管和电阻式存储器件的有前景的候选材料。溶液法制备的二维钙钛矿中自组装量子阱（QW）结构的显著存在提供了一系列多样的光电特性，而这些特性在很大程度上仍未被探索。在这里，我们通过实验观察到，由于自组装量子阱结构中自由载流子的量子限制形成了激子，自由载流子在20皮秒内实现了超快弛豫。此外，在刚性和柔性衬底上，将二维钙钛矿与超材料杂交，能够以50吉赫兹的调制速度调制太赫兹场，这对于溶液法制备的基于半导体的光子器件来说是最快的。因此，二维钙钛矿基于激子的超快响应为一系列可扩展的动态光子器件开辟了广阔的道路，这些器件在柔性光子学、超快波前控制和短程无线太赫兹通信中具有潜在应用。
