Giant and Broadband Multiphoton Absorption Nonlinearities of a 2D Organometallic Perovskite Ferroelectric.

Li, Maofan; Xu, Yanming; Han, Shiguo; Xu, Jinlong; Xie, Zhenda; Liu, Yi; Xu, Zhiyun; Hong, Maochun et al. · Adv Mater · 2020

basic_science · Level V

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Abstract

Multiphoton absorption (MPA) has been utilized for important technological applications. High-order multiphoton harvesting (e.g., five-photon absorption, 5PA) exhibits unique properties that could benefit biophotonics. Within this field, perovskite oxide ferroelectrics (e.g., BaTiO<sub>3</sub> ) enable low-order optical nonlinearities of 2PA/3PA processes. However, it is challenging to obtain efficient, high-order 5PA effects. Herein, for the first time, giant and broadband MPA properties are presented in the 2D hybrid perovskite ferroelectric (IA)<sub>2</sub> (MA)<sub>2</sub> Pb<sub>3</sub> Br<sub>10</sub> (1; IA = isoamylammonium and MA = methylammonium), where multiphoton-excited optical nonlinearities related to different MPA mechanisms over a broadband range of 550-2400 nm are observed. Strikingly, its 5PA absorption cross-section (σ<sub>5</sub> ) reaches up to 1.2 × 10<sup>-132</sup> cm<sup>10</sup> s<sup>4</sup> photon<sup>-4</sup> (at 2400 nm), almost 10 orders larger than some state-of-the-art organic molecules and a record-high value among all known ferroelectrics. This unprecedented 5PA effect results from the quantum-confined motif of inorganic trilayer sheets (wells) and organic cations (barriers) in 1. Moreover, its large ferroelectric polarization of 5 µC cm<sup>-2</sup> could promote modulation of MPA effects under external electric fields. As far as it is known, this is the first report on giant, broadband high-order MPA properties in ferroelectrics, which provides potential, novel electric-ordered materials for next-generation biophotonic applications.