Highly Enhanced Normalized‐Volume Multiphoton Absorption in CsPbBr₃ 2D Nanoplates

Abstract All‐inorganic perovskite nanocrystals (NCs) have attracted considerable attention due to their extensive photonic and optoelectronic properties. These NCs are shown to exhibit strong multiphoton absorption (MPA). However, studies on the MPA properties of perovskite NCs are only conducted on weakly confined perovskite cubic NCs, while the relevant influences of the geometry are never discussed. To the best of knowledge, this report describes the first comparison of the MPA properties of CsPbBr₃ 2D nanoplates (2D NPs) and cubic NCs. Based on the experimental results, it can be concluded that stronger quantum confinement effect of 2D NPs will strongly enhance their MPA with outstanding normalized‐volume two‐ and three‐photon absorption cross sections up to 1561 GM nm⁻³ and 7.2 × 10⁻⁷⁸ cm⁶ s² photon⁻² nm⁻³, respectively. This work demonstrates that CsPbBr₃ 2D NPs are good candidates for exploring the influences of quantum confinement on MPA properties of perovskite NCs, which are also highly suitable for the applications of multiphoton imaging and nonlinear optoelectronics.