Dielectric

Chemistry

Materials science

Optoelectronics

Composite material

Combinatorics

Physics

Crystallography

Nanotechnology

Mathematics

Optics

Perovskite (structure)

Femtosecond

Absorption (acoustics)

Inorganic chemistry

Laser

Saturation (graph theory)

Photonics

Iodide

Advanced Optical Materials

Organic–inorganic perovskites have attracted great attentions driven by exceptional progress in photovoltaics, photonics, and optoelectronics. Different from the corner sharing framework of 3D perovskite, 2D organic–inorganic perovskites possess a layered staking structure composed of alternative organic and inorganic components. Due to the inherent multi‐quantum‐well‐like structure, it is intriguing to explore the optical properties of 2D perovskites enabled by spatial and dielectric confinement. Herein, the two‐photon absorption (TPA) properties of 2D perovskite phenylethylamine lead iodide ((PEA) 2 PbI 4 ) are systematically studied. The 2D perovskite exhibits a giant TPA and saturation effect under excitation of 800 nm femtosecond laser. The TPA coefficient of a (PEA) 2 PbI 4 flake is measured to be about 211.5 cm MW −1 , which is at least one order of magnitude larger than those of 3D perovskite films and some typical semiconductor nanostructures. The giant TPA can be attributed to the enhanced quantum and dielectric confinement in the organic–inorganic multi‐quantum‐well structure. In addition, a highly thickness‐dependent TPA is observed for the 2D perovskite flakes. The result advocates a great promise of 2D organic–inorganic perovskites for nonlinear optical absorption related optoelectronic devices.

Giant Two‐Photon Absorption and Its Saturation in 2D Organic–Inorganic Perovskite