Halide Perovskites

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SPMS

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Laboratory name : Structures, Propriétés et Modélisation des Solide, UMR8580

Adress : 8 Rue Joliot Curie, 91190 Gif sur Yvette

Contact : Anne Spasojevic, anne.spasojevic centralesupelec.fr

Topics :
Our objective is to discover the materials of the future around major issues such as energy, electronics or health. Our strength is to work both on the exploration of new compositions, new ways of elaboration, but also on the advanced characterization of the structural and functional properties of the materials produced. We have thus developed a diffraction center where we can measure by XRD the structural properties in situ (low/high temperature, with/without electric field, under controlled atmosphere) for samples in the form of powders, thin layers or single crystals. These structural studies are supplemented by the use of Raman spectroscopy (low/high temperature) with excitation lengths from the visible to the ultraviolet. Finally, we also have an electrical measurement center for measuring electronic or ionic conductivity under temperature (low/high) and controlled atmosphere. Another important objective is to develop theoretical tools to understand matter from a sub-atomic scale to a scale of several hundred microns : DFT, molecular dynamics, 2nd principle methods. This understanding by modeling at the atomic scale is supplemented by the use of observation methods at the atomic scale thanks in particular to the MET Titan cube available in the laboratory, benefiting from a super EDX, imaging EELS, tomography/holography and specific sample holders for applying an electric field or heating the sample.
As the world mobilizes to combat the disastrous effects of climate change, researchers have been investigating novel means of using sustainable materials for renewable energy harvesting. One promising material is the Ruddlesden–Popper Hybrid Perovskite Halides (RPHPH), an optoelectronic material that can be produced in solution to be used for solar cells. Different approaches have been used to crystallize this material, but they produce multiple nuclei, remain prone to defects, or are not scalable. Ideally, this crystal should be a thin 2-D single crystal, but due to the lack of fundamental information for how it is formed, there is a lack of control over the nucleation process. Our team aims to launch a full investigation into the use of a high-throughput batch robotic device that crystalizes this material using an advanced nucleation technique known as Non-Photochemical Laser-Induced Nucleation (NPLIN). NPLIN can control an otherwise random and time-consuming nucleation process and provide temporal and spatial control over nucleating crystals—only inducing nucleation in the beam path in a matter of seconds as opposed to days. We have crystallized MAPbBr3 and FAPbBr3 using a femtosecond pulsed laser. The results have shown that two different mechanisms (one step and two steps nucleation) are involved depending on the compound.

Experimental means / theoretical tools :

  • Optical Microscopy, Raman diffusion and powder or single crystal Xray diffraction.
  • Laser-Induced nucleation robot
  • Comsol simulations
  • MET Titan cube