Anisotropic shape of CsPbBr₃ colloidal nanocrystals: from 1D to 2D confinement effects

Abstract

We synthesized strongly anisotropic CsPbBr3 nanocrystals with very narrow emission and absorption lines associated to confinement effects along one or two dimensions, called respectively nanoplatelets (NPLs) and nanosticks (NSTs). Transmission...

Dielectric Confinement and Exciton Fine Structure in Lead Halide Perovskite Nanoplatelets

“…They almost compensate each other down to L z ≈ a X , explaining the stability of ∆ in Figure 1b. This prediction is in agreement with the behavior experimentally observed on CsPbBr 3 NPLs [28], with a thickness dependence for the excitonic energy such as…”

“…A strong weakening of the high energy absorption transition associated to the dipole oriented along the more confined dimension (ground state to |0 B or |Z transitions) is indeed expected. Taking into account the inhomogeneous broadening we will finally obtain an asymmetry in the absorption profile consistent with the experimental observations [28].…”

“…We have only reported exciton energies deduced from absorption measurements on CsPbBr 3 NPL, because photoluminescence is generally Stokes shifted and underestimates the exciton energy. A very good agreement is obtained between the data from the work in [28] and the calculated exciton energy in presence of a dielectric mismatch, for 4 to 11 monolayers thicknesses. Nonetheless, the theory overestimates the emission measured in [29].…”

“…The knowledge of FSS is of prime importance otherwise to design quantum devices like optical sensors or single-photon sources. In the presence of Coulomb interactions and dielectric mismatches, the energy levels are sensitive to three important contributions (e-h Coulomb attraction, single-particle self-energy, and kinetic energy) which mostly compensate each other, leading to a quasi-constant red-shift ∆ of the free e-h pair energy, recently observed in CsPbBr 3 NPLs [28]. Due to the 2D geometry, the excitonic bright triplet degeneracy is partially lifted in the cubic phase, a behavior different from what has been observed in cubic-shaped nanocrystals where the three bright states (|+1 , |−1 , |0 B ) are fully degenerate.…”

Unexpected Anisotropy of the Electron and Hole Landé g-Factors in Perovskite CH3NH3PbI3 Polycrystalline Films

“…In addition, these materials are also promising for opto-spintronic devices [10,11] because they show long spin lifetimes [12][13][14][15], chiral properties [16][17][18], and large Rashba splitting [19]. The synthesis of engineered nanostructures [20][21][22] extends the future applications of these materials to the domain of quantum optics and quantum information processing.…”