Cesium–Lead Bromide Perovskite Nanoribbons with Two-Unit-Cell Thickness and Large Lateral Dimension for Deep-Blue Light Emission

Two-dimensional (2D) lead halide perovskites (LHPs) are the junction of two hot areas of 2D materials and LHPs, which possess unique chemical and physical properties and deserve in-depth studies. However, because of their intrinsic nonlayered nature, it is challenging to directly synthesize 2D LHPs, especially with large lateral sizes. Herein, we propose a facile colloidal method to obtain 2D large-area CsPbBr3 perovskites. By employing protonated oleylamine as the strong binding ligand, the anisotropic growth of the perovskite is facilitated, resulting in a 2D architecture. Moreover, by using octane as the antisolvent in the recrystallization procedure, the number of nuclei could be efficiently reduced so that most of the reactants are consumed for growth, guaranteeing a lateral size extension. The final CsPbBr3 nanoribbons exhibit two-unit-cell thickness and large lateral size of up to several micrometers, boosting the thickness limit for 2D large-area free-standing CsPbBr3. Thanks to the strong quantum confinement effect driven by the ultrathin thickness, our products exhibit great potential for deep-blue light emission.