Material Synthesis & Processing

SOPHY will investigate the role of the deformable nature of the crystal lattice in metal halide perovskite semiconductors in the determination of the material “defectiveness”. In principle, the electronic properties of metal halides perovskites are defined by the (Pb)(X3-xYx) network. However, conformational disorder and lattice deformations can perturb the electronic landscape within the Pb-X. The presence of various types of chemical interactions in such complex ionic solids gives them a characteristic “soft” fluctuating structure, prone to a wide set of defects which may span from lattice distortions to the presence of mobile ions. Therefore, the defectivity of these materials is strongly dependent on the synthetic design as well as the processing conditions adopted for the thin film fabrication.

The project will address:

• synthesis of precursors for 3D and 2D metal halide perovskites and synthesis of colloidal nanocrystals
• thin film processing and characterization. XRD and XPS to study the structural and chemical quality of the thin films; Raman and Photoluminescence (PL) Spectroscopy to probe optical and structural disorder in perovskites. Time resolved PL, supported by PL quantum yield measurements, also coupled to a confocal microscope for sample mapping with simultaneous measurement of photocurrent, for a primary and rough screening of the relevant mechanisms of carrier recombination.