Controlled generation of reactive oxygen species (ROS) is essential in biological, chemical, and environmental fields, and piezoelectric catalysis is an emerging method to generate ROS, especially in sonodynamic therapy due to its high tissue penetrability, directed orientation, and ability to trigger in situ ROS generation. However, due to the low piezoelectric coefficient, and environmental safety and chemical stability concerns of current piezoelectric ROS catalysts, novel piezoelectric materials are urgently needed. Here, we demonstrate a method to induce polarization of inert poly(tetrafluoroethylene) (PTFE) particles (<d > ~ 1–5 μm) into piezoelectric electrets with a mild and convenient ultrasound process. Continued ultrasonic irradiation of the PTFE electrets generates ROS including hydroxyl radicals (•OH), superoxide (•O2−) and singlet oxygen (1O2) at rates significantly faster than previously reported piezoelectric catalysts. In summary, ultrasonic activation of inert PTFE particles is a simple method to induce permanent PTFE polarization and to piezocatalytically generate aqueous ROS that is desirable in a wide-range of applications from environmental pollution control to biomedical therapy.

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., BaTiO3) 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)2(MA)2Pb3Br10 (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 (σ5) reaches up to 1.2 × 10−132 cm10 s4 photon−4 (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−2 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.

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