Aspect Ratio and Quantum Confinement Tunable Giant Two-Photon Absorption from 1D CsPbI₃ Perovskite Nanorods

Herein, we investigate the influence of aspect ratio and quantum confinement on the single-photon (σ₁) and two-photon absorption cross-section (σ₂) for perovskite CsPbI₃ nanorod (NR). Notably, experimentally measured data show extremely high σ₂ for CsPbI₃ NR (10.8 × 10⁷ GM) which is five orders of magnitude higher than organic chromophores, and two order of magnitude higher than CsPbBr₃ nanocrystals. Moreover, σ₂ for NRs can be enhanced by two-orders of magnitude by varying the aspect ratio and σ₁ enhances linearly with aspect ratios. Furthermore, experimental data show moderate quantum confinement effect on the volume-normalized σ₁ and σ₂ for nanorods.