Size- and Wavelength-Dependent Two-Photon Absorption Cross-Section of CsPbBr₃ Perovskite Quantum Dots

Abstract

All-inorganic colloidal perovskite quantum dots (QDs) based on cesium, lead, and halide have recently emerged as promising light emitting materials. CsPbBr QDs have also been demonstrated as stable two-photon-pumped lasing medium. However, the reported two photon absorption (TPA) cross sections for these QDs differ by an order of magnitude. Here we present an in-depth study of the TPA properties of CsPbBr QDs with mean size ranging from 4.6 to 11.4 nm. By using femtosecond transient absorption (TA) spectroscopy we found that TPA cross section is proportional to the linear one photon absorption. The TPA cross section follows a power law dependence on QDs size with exponent 3.3 ± 0.2. The empirically obtained power-law dependence suggests that the TPA process through a virtual state populates exciton band states. The revealed power-law dependence and the understanding of TPA process are important for developing high performance nonlinear optical devices based on CsPbBr nanocrystals.

Recent Progress in Metal Halide Perovskite Micro‐ and Nanolasers

“…First, they demonstrated that TPA cross‐section for CsPbBr 3 is proportional to the linear one‐photon absorption. The TPA cross‐section follows a power law dependence on QDs size (4.6–11.4 nm) with exponent 3.3 ± 0.2 . For the TPA process, the number of excitons created 〈 N 〉 relates to the pump fluence F by 〈 N 〉 = σ 2PA F /τ, where σ 2PA is the TPA cross section, F is the fluence in photons cm −2 , and τ is the laser pulse width.…”

“…Copyright 2016, American Chemical Society. (b) Reproduced with permission . Copyright 2017, American Chemical Society.…”

Two-Dimensional Halide Perovskites for Emerging New- Generation Photodetectors

“…For example, Chen et al have recently revealed that the TPA process proceeds through a virtual level and then ended in an exciton band state. This observation would lay a solid physic basis for the development of high-performance nonlinear optical perovskite materials [86].…”

Giant two- to five-photon absorption in CsPbBr27I03 two-dimensional nanoplatelets

“…where AI ∕I 0 represents the GSB signal amplitude of the 2D NPs after a long time delay, and I 0 is the minimal excitation light intensity used [19]. The GSB signal amplitudes of the 469 nm and 527 nm 2D NPs, for different excitation light intensities, were collected for the decay time of 1 ns, and the results are shown in Figs.…”