UV-Assisted Conversion of 2D Ruddlesden-Popper Iodide Perovskite Nanoplates into Stable 3D MAPbI3 Nanorods

Quantum-confined two-dimensional (2D) Ruddlesden-Pop-per (RP) perovskite nanoplates (NPls) are drawing considerable attention in recent times. The effect of external perturbations like air, moisture, heat, polarity of the solvent, and, specifically, light irradiation has significant impact on the RP perovskite structure in different ways. Though some reports are available on the effect of light irradiation on RP NPl single crystals, films, and flakes, no comprehensive study is available for the RP NPl colloidal state. To extend the understanding, we studied the fate of UV irradiation on a colloidal, orange-em itting oleylammonium iodide-based RP NPl, (C18H35NH3)2(CH3NH3PbI3)2PbI4 (n = 3). A constant UV exposure for 10 h transforms the RP NPl structure into a purely 3D methylammonium lead iodide (CH3NH3PbI3, MAPbI3) nanorod (NR) having a photo-luminescence quantum yield of 65%. Our experimental results reveal that this structural transformation takes place by ligand desorption, followed by structural association in an oriented fashion. The obtained MAPbI3 NR shows excellent optical and crystalline phase stability for more than 2 months.