CNRS – Updates

During the past year, CNRS and INSA capitalized both on the concepts and tools implemented for the PEROCUBE project to push further the frontiers of perovskite devices. Based on the concept of in-plane lattice matching and prediction of energy level alignments, we proposed new combinations of 2D and 3D perovskites. The 3D perovskite has a structural network made of corner-sharing octahedra through the halides in all three directions. On the other hand, when adding a larger cation to perovskite precursors, lower dimensional structures may form. Among them are layered perovskites that resembles the creamy French millefeuille, with the big cation templating and stabilizing the 2D inorganic perovskite sheets.

The proposed combination of  2D and 3D were successfully implemented, on one hand by partners from Oxford who made more stable and efficient LEDs of various colors, and on the other hand, by our longstanding collaborators at Rice University for PV devices. It enabled to stabilize the perovskite phase of the best suited 3D composition, namely formamidinium lead iodide three, which is otherwise metastable and easily turns into its non-photoactive yellow phase ⟨10.1126/science.abq6993⟩. The 2D seeds added to the precursor solution offers a slightly compressed template that stabilizes the perovskite phase.

They further exploited new theoretical framework designed to afford a relationship between surface and interface dipoles and the materials energetics along with atomistic information to investigate lead-free compositions ⟨10.1002/admi.202400201⟩. They also pursued their quest toward atomistic approaches presenting the best compromise between accuracy and computational cost. With their collaborators from Bremen University they developed DFTB parameters specifically adapted for predicting the electronic structure of 3D, 2D iodide perovskites and heterostructures made of several thousands of atoms ⟨10.1103/PhysRevMaterials.9.023803⟩.

They in Rennes are very keen to contribute in this direction in future European projects, being convinced that fundamental research can further contribute to a sustainable transition while educating future generations.