Defects Activity in Wide and Narrow Bandgap Metal Halide Perovskite Semiconductors

<br/>Metal halide perovskites (MHPs) have demonstrated huge potential to build a rich library of materials for a new disruptive optoelectronic technology. The main strength comes from the possibility of easily tune the semiconductor bandgap in order to integrate it in devices with different functionalities – in principle. In reality, this cannot be achieved yet. In fact, while defect tolerance is claimed for MHPs with a bandgap of about 1.6 eV, the model system object of intense investigations, MHPs with lower and higher bandgaps are far from this claim. They show various forms of instabilities which are mainly driven by a strong defect activity.<br/><br/>Here I will discuss our studies on the nature of defects and their photo-chemistry as a function of the semiconductor bandgap and chemical composition in order to identify their role in defining the semiconductor electronic properties and stability.