Lead Iodide Thin Films via rf Sputtering
José Maria Clemente da Silva Filho, Nelson Fabián Villegas Borrero, Gustavo A. Viana, Rafael Borges Merlo, F. C. Marques
Abstract
Lead iodide (PbI2) is a precursor for the preparation of the organolead iodide perovskite (CH3NH3PbI3), which has been used in the fabrication of highly efficient solar cells. In this work, a novel route for the deposition of PbI2 thin films is performed by rf sputtering a target made from compressed PbI2 powder. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that the PbI2 films produced were uniform, pinhole-free, polycrystalline, and had low roughness. A small concentration of Pb nanocrystals observed within the films is attributed to differences in the sputtering yield of lead and iodide from the PbI2 target. A dependence of band gap on rf sputtering power was observed, which was associated with a reduction in the concentration of Pb nanocrystals. The PbI2 films were efficiently converted into CH3NH3PbI3 perovskite films through the immersion into a methylammonium iodide (MAI) solution, which also converted the remaining Pb nanocrystals into perovskite. This methodology has the potential to forge the way toward a new method for the fabrication of large-area perovskite solar cells.