EMISSIVE NANOCRYSTALS FOR OPTOELECTRONIC APPLICATIONS

Metal halide perovskites (particularly doped perovskites and lead free double perovskites) are starting to generate great interest in the scientific community due to their unique electronic and structural properties, such as high photoluminescent quantum yields (PLQY, up to 90%), chemical diversity in terms of elements employed and tunable optical properties. Consequently, their application in optoelectronic devices gained attention. During these three years, I intensively worked on the synthesis and characterization of inorganic perovskites nanocrystals, starting from lead halide perovskites (LHPs) in 3D and 0D structure and then moving to the double perovskites (DPs). Generally, the aim of these studies is to replace Pb with less toxic elements, producing materials more stable to atmosphere conditions and with good optical properties. Thus, synthesis and optimization are the key words of this part of the work. Pb has been replaced with a monovalent (Ag, Na) and a trivalent (In, Bi), or a bivalent (Cu, Mn) and a trivalent (Sb) metal cation, leading to DPs (e.g. Cs2AgInCl6) and layered perovskites (e.g. Cs4CuSb2Cl12), respectively. However, perovskites are not the only promising candidate for optoelectronic devices, in particular considering the increasing interest in studying NIR emitting materials. In this field, my work on silicates takes place. In fact, Cu - based silicates (e.g. CaCuSi4O10) possess a high emission in NIR region (900–1000 nm). Moreover, their high Stokes shift, which limits re-absorbance phenomenon, and the high stability to ambient condition and sun irradiation, suggest their use in solar absorbing devices. During my PhD I performed deep structural investigation using synchrotron radiation after an optimization of the material synthesis; then, I worked on their exfoliation leading to the formation of very homogeneous nanosheets.