Controllable transformation between 3D and 2D perovskites through cation exchange

A facile post-synthesis cation exchange approach has been employed to controllably tune the optical and structural properties of colloidal perovskite nanocrystals (NCs). These optical changes are attributed to the structural transformation of perovskite NCs from three-dimensional (3D) to two-dimensional (2D) layered crystalline forms and vice versa.