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.

Improved One- and Multiple-Photon Excited Photoluminescence from Cd2+-Doped CsPbBr3 Perovskite NCs

“…For both samples, the wavelength dependencies of the 3PA cross-sections well matched the linear absorption spectra of the NC solutions, except the region of intense absorption of toluene (1340–1440 nm). This observation is in line with previously reported wavelength dependencies obtained for both 2PA and 3PA in CsPbBr 3 NCs [ 64 , 68 ].…”

“…The reported NC values of third-order nonlinear optical parameters strongly depend on their stoichiometry [ 63 ], size [ 64 ], and shape [ 65 ]. The value obtained for the pristine CsPbBr 3 NCs (3.2 ± 1.9) × 10 5 GM was very close to those recently reported (see Table 1 ) [ 64 , 65 , 66 , 67 , 68 ]. CsPb 0.78 Cd 0.22 Br 3 NCs demonstrated an almost one-order enhanced value of the 2PA cross-section, and the obtained value is among the highest reported for CsPbBr 3 NCs [ 69 , 70 ].…”

Advances of Nonlinear Photonics in Low‐Dimensional Halide Perovskites

“…[80] These results indicate the 2PA in the cubic CsPbBr 3 QDs is mainly determined by the volume of the QDs, rather than the quantum confinement effect. By contrast, in some other recent studies, [88,89] it was found 2D CsPbBr 3 nanoplates (NPs) with the thickness <2 nm possess much stronger volume normalized 2PA cross-section (NV σ (2) ≈ 10 3 GM nm −3 ) than the cubic NCs (Figure 4G-I). These NLO results are consistent with a stronger quantum confinement effect shown in the 2D NPs with a stronger and sharper exciton absorption peak and higher exciton binding energy compared to the cubic counterpart.…”

Water Triggered Synthesis of Highly Stable and Biocompatible 1D Nanowire, 2D Nanoplatelet, and 3D Nanocube CsPbBr3 Perovskites for Multicolor Two-Photon Cell Imaging

“…Our observed highest VN 2PA cross-section for 2D nanoplatelets can be due the higher transition dipole moment attributed to stronger confinement effect than that of 3D nanocubes and 1D nanowires. 50 , 53 , 54 To understand whether the PEG coating enhances the 2PA cross-section for 1D, 2D, and 3D CsPbBr 3 nanocrystals, we also measured the 2PA cross-section for 1D, 2D, and 3D CsPbBr 3 nanocrystals with PEG. Using Z-scan data, we determined 2PA coefficients of 1D, 2D, and 3D nanocrystals, and these are σ 2 ∼ 2.1 × 10 5 GM for 1D nanowires, σ 2 ∼ 4.9× 10 5 GM for 2D nanoplatelets, and σ 2 ∼ 8.5 × 10 4 GM for 3D nanocubes, which are very similar to the 2PA properties for PEG coated 1D, 2D, and 3D CsPbBr 3 nanocrystals.…”