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The photovoltaic performance of perovskite solar cells (PVSCs) is extremely dependent on the morphology and crystallization of the perovskite film, which is affected by the deposition method. In this work, a new approach is demonstrated for forming the PbI 2 nanostructure and the use of high CH 3 NH 3 I concentration which are adopted to form high‐quality (smooth and PbI 2 residue‐free) perovskite film with better photovoltaic performances. On the one hand, self‐assembled porous PbI 2 is formed by incorporating small amount of rationally chosen additives into the PbI 2 precursor solutions, which significantly facilitate the conversion of perovskite without any PbI 2 residue. On the other hand, by employing a relatively high CH 3 NH 3 I concentration, a firmly crystallized and uniform CH 3 NH 3 PbI 3 film is formed. As a result, a promising power conversion efficiency of 16.21% is achieved in planar‐heterojunction PVSCs. Furthermore, it is experimentally demonstrated that the PbI 2 residue in perovskite film has a negative effect on the long‐term stability of devices.
Zhang et al. (2015) studied this question.