Within what can be defined as a renaissance of perovskite-based materials, the organic-inorganic hybrid compounds of lead halides, in particular, have marked the opening of new horizons in the research of new materials for energy. The rediscovery of the optoelectronic characteristics of such materials integrated into photovoltaic devices, for example, has promoted an unexpected progress in terms of efficiency thanks to the surprising properties demonstrated (high absorption coefficients, high carriers mobility, etc.). At the same time, these results encouraged the scientific community to explore the potential of the perovskites in a much wider range of possibilities, considering also the margins of improvement linked to the well-known problems of stability and degradation (effects of light and moisture, ion migration, phase segregation). In particular, the perovskites in the form of nanocrystals have shown a strong interest in the field of materials for emission thanks to the extremely positive repercussions of the size reduction, in the optical properties of photoluminescence and the photoluminescence quantum yield. [1] On the other hand, in this last case new problems emerged, related to the synthesis, stability and preparation of materials that can be integrated in an actual device. The most common colloidal synthesis, in fact, generally involves high-cost procedures and does not allow such an effective control on the nanometer scale causing aggregation phenomena above all at the time of depositing these materials in the form of thin films and thus losing the optical qualities.

Herein I present a method for the synthesis of APbX₃ perovskite nanocrystals which allows to control the crystal size up to few nanometers, using porous inorganic matrices composed of different mesostructured metal oxides (MOx) [2]. With these systems it is possible to achive the effects of quantum confinement on the optoelectronic properties of the perovskites (spectral control of the emission in the entire visible range, high PLQY) and combine them with the value imported from the matrices. In this way, for example, it is possible to obtain transparent, but narrow band highly luminescent films due to the homogeneous distribution of perovskite nanocrystals. It is still possible to further functionalize these perovskite/MOx composite systems with polymeric materials and to obtain flexible films capable of emitting light with particularly high quantum yields (PLQY>50%) even in conditions of extreme humidity. In fact, the polymer impregnation gives greater stability and offers an effective barrier against the typically degradation cause by water [3]. This material can found applications as color converting layers and in emission devices as it is demonstrated in this work.