Abstract . Metal halide perovskites (MHPs) constitute a rich library of materials with huge potential for disruptive optoelectronic technologies. Their main strength comes from the possibility of easily tuning their bandgap to integrate them in devices with different functionalities — in principle. In reality, this cannot be achieved yet. In fact, whereas defect tolerance can be claimed for MHPs with a bandgap of about 1.6?eV, the model system that is the object of intense investigations, ...