Speaker
Description
Perovskites have become a popular material system for fabricating photovoltaics and various optoelectronic devices. Different variations of solution-processing by spin-coating have been investigated over the years. However, perovskites can also be deposited by thermal evaporation. This technique offers the unique possibility to accurately control the deposition of smooth and uniform multilayers of perovskite materials, without the need for thermal annealing and avoiding the use of toxic solvents. E-beam evaporation is a subclass of thermal evaporation that enables to control more accurately the film growth thanks to a local heating of the precursors and a reduced deposition rate. Films produced in this way will be adequate for characterization through photo-emission electron microscopy and X-ray ultrafast spectroscopy. The goal is the fabrication of thin, uniform and smooth PSCs of different dimensionalities and chemical compositions. The e-beam setup optimization is currently ongoing using as prototype material all inorganic CsPbI3. This composition is particularly suitable because only the correct stoichiometry allows the growth of the film in the perovskite phase at room temperature.
Fabricated samples will be deeply characterized to validate their quality. Their physics will be elucidated as a function of their chemical and structural characteristics, as well as thin-film processing. For this reason, in parallel to the optimization of the vapor deposition method, solution-processed perovskite FaCsSnI3 is investigated. The optical quality of the samples is validated by the characterization of the emissive properties of the thin film i.e. photoluminescence quantum yield and transient dynamics. The surface characterization will be based on photo-emission electron microscopy (Time-resolved PEEM) to clarify the peculiar physic of defects and structural-property relationship exploited in the relation among molecular interactions, structural deformations, and optoelectronic properties.
