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

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. How dimensionality influences the multiphoton absorption properties of all‐inorganic lead halide perovskite nanocrystals is not established to date. An experiment described in this report clearly demonstrates that the quantum confinement of 2D CsPbBr3 nanoplates can efficiently enhance their normalized‐volume two‐ and three‐photon absorption compared to cubic nanocrystals. [ABSTRACT FROM AUTHOR]