How stable Is the 2D/3D interface of metal halide perovskite under light and heat?

A (PEA)2PbI4 (2D) layer deposited on a MAPbI3 (3D) film undergoes a transformation upon photoirradiation and thermal treatment. The decrease in absorption and emission of the 2D layer during light and heat exposure, which shows migration of the PEA+ cation within the 3D film, points out the dynamic nature of the 2D/3D interface and intermixing of the two phases.