EnVironmentally friEndly pSeudohalides mixed compounds for tunable Photoactive pErovskite mateRials (VESPER)

New lead(II) or copper(I) mixed halide-pseudohalide materials will be synthesized to obtain environmentally friendly photoactive materials and overcome the drawbacks of traditional perovskites. This ambitious goal will be achieved using recycled materials as reactants and exploiting procedures such as quasi- or totally solvent free as mechanochemistry. Moreover, their stability to moisture and temperature for a control of the release of the potentially dangerous components will be investigated to design strategies able to mitigate such effect. All the obtained materials will be analysed with SCXRD (single crystal X-ray diffraction) and with all the different vibrational spectroscopies (Infrared, from NIR to FIR, and Raman spectroscopies), to understand both the factors governing the structural details and the lattice dynamics, which can be of great importance in electronic properties. Through Uv-Vis absorption and emission spectroscopies, information about their electronic properties and band gap will be gathered in order to obtain a structure property relation on these aspects. The same will be done with conduction properties, that are fundamental for photoelectric materials. When the most promising materials will be obtained and selected, an in depth study of the solution speciation (with ESI MS and other non-perturbative techniques) will be performed to connect the solution and solid-state. An optimization of the crystal growth and morphology will be performed on most promising phases through in-situ and in-operando techniques, to obtain the highest degree of crystallinity in the products, a very important parameter in these materials. Moreover, the high-pressure crystallography and optical techniques will be used to tune more finely the band gap. At the same time, phenomena of great technological importance as piezochromism (change of colour with pressure), pressure induced metallization and phase transitions will be searched and, if present, detected and studied. A special technological challenge of VESPER project is to synthesize new materials which can overcome the actual known limitation of peroVskite solar cell devices, increasing the advantages during production, employ and dismission, such as easy bandgap tunability, low fabrication cost, recycling waste materials, with an environment friendly production, without solvents and stabilizing toxic inorganic materials such AS lead and CN