Controlling Anisotropy of Quantum-Confined CsPbBr₃ Nanocrystals by Combined Use of Equilibrium and Kinetic Anisotropy

Anisotropic semiconductor nanocrystals with controlled quantum confinement are important in many applications for the directionality of the flow of photons and charge carriers combined with the properties of confined exciton. Here, we report the strategy that introduces controlled morphological anisotropy with one- and two-dimensional confinements in CsPbBr₃ nanocrystals via the simultaneous use of thermodynamic equilibrium and kinetic anisotropy. In this approach, the halide equilibrium recently shown to control the size of zero-dimensional perovskite quantum dots under hot-injection condition is combined with the anisotropic growth kinetics that becomes more prominent at a lower temperature. Nanoribbons, nanowires, and nanoplatelets exhibiting well-defined confined exciton transition and high-emission polarization anisotropy were obtained at room temperature. While two seemingly incompatible modes of size control (equilibrium and kinetics) are combined, each mode controls the size in a different direction of the anisotropic perovskite nanocrystals, enabling the simultaneous control of confinement and morphological anisotropy.