Fully Ambient-Processed Perovskite Film for Perovskite Solar Cells: Effect of Solvent Polarity on Lead Iodide.

Fully ambient-processed and highly efficient methylammonium lead iodide (MAPbI3) perovskite films are very desirable for industrial manufacturing of perovskite solar cells (PSCs). To date, most reported highly efficient MAPbI3 PSCs rely on the fabrication of lead iodide (PbI2) films inside the glovebox. Here we report a simple fabrication method using extra dry isopropanol (IPA100) for obtaining uniform and loosely packed PbI2 film, which leads to a uniform and highly crystalline MAPbI3 film under ambient conditions. Compared with recently reported results (10%-15%) using IPA treatment in the glovebox, we achieved over 16% efficiency of PSCs while fabricating perovskite films in fully ambient conditions. We have found the removal of even trace amounts of water from IPA to be a key factor for the successful ambient fabrication of PbI2 films, as the high polarity of water negatively influences the crystallinity and morphology of the PbI2 film.