Electronic Doping of Soft Semiconductors

EDO will develop protocols for intentional, spatially controlled, and stable electronic doping in metal halide semiconductors.Electronic doping implies engineering of carrier density in semiconductors through the intentional introduction of a defect and it is necessary to achieve high performances in micro and optoelectronic technologies. Unlike established semiconductors, which are typically covalent solids, those belonging to the class of soft materials, such as molecules and polymers, forming van der Waals solids, and metal halide perovskites, forming ionic solids, host complex doping mechanisms. As a result, the design of free carrier density is far from being established and exploited in metal halides perovskites thin films. Intrinsic challenges, such as compensation and migration of defects, charge localization, phase segregation and the strong doping−processing relationship, may hide or hamper the designed doping process. Characterization and control of such phenomena require the combined knowledge of electronic, chemical and morphological/structural information, which is often missing. As a result, reports are often contradictory and advanced tools are in demand to draw a complete picture. Synchrotron facilities may help reaching the target, however, their limited access hampers direct feedback between synthesis and characterization.EDO will develop an unprecedent multimodal experimental tool, in laboratory environment, to quantitatively assess the doping and examine its impact on the optoelectronic properties of metal halides perovskites semiconductors. A photoemission microscope will be coupled to tunable coherent sources, covering the entire spectrum from NIR to soft X-ray radiation to map at nanometer scale the Fermi level shift, the electronic structure and the elemental composition and organization of thin films, and the relative optoelectronic dynamics, transferring the secured knowledge to the development of materials processing.