Surface-activation modified perovskite crystallization for improving photovoltaic performance

An improved vapor-phase deposition that leveraged the use of surface activation of PbI2 film has been developed for modifying perovskite crystallization process. This was achieved by loading Cl- ligands on closely-packed PbI2 particle film-a scaffold that allowed in situ formation of perovskite active layer. The introducing of Cl- ligands served the Cl(-)capped and thus electrostatically-charged PbI2 nanoparticles showed improved colloidal stability in DMF, which facilitated the preparation of PbI2 film. More importantly, during the process of CH3NH3I (MAI) deposition i. e. the growth of perovskite materials, the presence of three-dimensional Cl- ligand matrix favored the formation of dense perovskite film. Moreover, a desired release of chloride was also achieved, thus promote the rearrangement of the perovskite during the volume expansion process. This finally led to a PCE of PSCs exceeding 16.42% under AM 1.5 irradiation. Therefore, surface-activation with Cl-ligand matrix could provide guidelines for the morphology optimization and the perovskite devices performance enhancement. (C) 2017 Elsevier Ltd. All rights reserved.