Annamaria Petrozza1

1, Istituto Italiano di Tecnologia, Milano, , Italy

Semiconducting metal-halide perovskites present various types of chemical interactions which give them a characteristic fluctuating structure sensitive to the operating conditions of the device, to which they adjust. This makes the control of structure-properties relationship, especially at interfaces where the device realizes its function, the crucial step in order to control devices operation. In particular, given their simple processability at relatively low temperature, one can expect an intrinsic level of structural/chemical disorder of the semiconductor which results in the formation of defects.
Here I will discuss the role of defect physics in determing the open circuit voltage of metal halide perovskite solar cells and present strategies for the optimization of devices which include: 1) the engineering of the charge extracting layer (CEL), which accounts not only for the energy level alignment between the CELs and the perovskite, but also for the quality of the microstructure of the perovskite bulk film that is driven by the substrate surface; and 2) the use of inks based on colloidal suspensions of nanoparticles which lead to a high level of control over the material quality and device reliability, and offer more versatile processing routes by decoupling crystal growth from film formation.