Lu Shunbin, Zhou Feng, Zhang Qi, Eda Goki, Ji Wei
SZU-NUS Collaborative Innovation Centre for Optoelectronic Science and Technology International Collaborative Laboratory of 2D Materials for Optoelectronic Science and Technology of Ministry of Education College of Optoelectronic Engineering Shenzhen University Shenzhen Guangdong 518060 P. R. China.
Department of Physics National University of Singapore Singapore 117551 Singapore.
Adv Sci (Weinh). 2018 Dec 20;6(4):1801626. doi: 10.1002/advs.201801626. eCollection 2019 Feb 20.
Multiphoton absorption may find many technological applications, such as enhancing the conversion efficiency of solar cells by the utilization of sub-band-energy photons, below-bandgap photodetection through the simultaneous absorption of several infrared photons for photocurrent generation, or light frequency upconversion for high-resolution, 3D imaging. To enhance multiphoton absorption in semiconducting materials, one of the strategies is to explore low-dimensional excitons. Here, a quantum perturbation theory on a giant enhancement in three-photon absorption (3PA) arising from 2D excitons in multilayered crystals of organic-inorganic hybrid perovskites is presented. The maximal 3PA coefficient is predicted to be in the range of 2-7 cm GW at 1100 nm, the largest values reported so far for any 2D and bulk semiconductors at room temperature. Excellent agreement between theory and the experimental findings unambiguously demonstrates a pivotal role in the enhancement of 3PA played by 2D excitons. The theory predicts that the resonant 3PA coefficient should be enhanced further by at least two orders of magnitude with very low temperature. The findings are essential for understanding giant 3PA arising from 2D excitons in layered hybrid perovskites and may open new pathways for highly efficient conversion from infrared light energy to either electrical energy or higher-frequency light emission/lasing.
多光子吸收可应用于多种技术领域，例如通过利用子带能量光子提高太阳能电池的转换效率，通过同时吸收多个红外光子产生光电流实现带隙以下的光电探测，或用于高分辨率三维成像的光频率上转换。为了增强半导体材料中的多光子吸收，其中一种策略是探索低维激子。在此，我们提出了一种量子微扰理论，用于解释有机-无机杂化钙钛矿多层晶体中二维激子引起的三光子吸收（3PA）的巨大增强。预测在1100 nm处最大3PA系数在2-7 cm GW范围内，这是目前报道的任何二维和体半导体在室温下的最大值。理论与实验结果的出色吻合明确证明了二维激子在增强3PA中所起的关键作用。该理论预测，在极低温下，共振3PA系数应至少再提高两个数量级。这些发现对于理解层状杂化钙钛矿中二维激子产生的巨大3PA至关重要，并且可能为从红外光能高效转换为电能或更高频率的光发射/激光开辟新途径。
