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 (MAPbI 3 ) perovskite films are very desirable for industrial manufacturing of perovskite solar cells (PSCs). To date, most reported highly efficient MAPbI 3 PSCs rely on the fabrication of lead iodide (PbI 2 ) films inside the glovebox. Here we report a simple fabrication method using extra dry isopropanol (IPA100) for obtaining uniform and loosely packed PbI 2 film, which leads to a uniform and highly crystalline MAPbI 3 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 PbI 2 films, as the high polarity of water negatively influences the crystallinity and morphology of the PbI 2 film.