intermediate phase is another very effective way to transfer a uniform and high-quality perovskite fi lm because the intermediate phase can slow down the reaction between PbI 2 and FAI in solution. [ 27 ] Recently, intramolecular exchange has been shown to dramatically improve the power conversion effi ciency of perovskite solar cells (PSCs), and such exchange of DMSO intercalated in PbI 2 (PbI 2 (DMSO) complex) with FAI leads to crystallization of FAPbI 3 because FAI has a higher affi nity for PbI 2 than does DMSO. [ 9 ] This exchange neither increased the volume nor changed the thickness of the as-coated PbI 2 (DMSO) fi lm because the molecular sizes of FAI and DMSO are similar, and hence a stable, dense, and uniform perovskite fi lm was fabricated.The intercalation of layered PbI 2 with different organic molecules has been studied a useful method to fabricate inorganic-organic compounds with novel properties. [ 28 ] The structure of PbI 2 consists in sandwich-type layers, which contains a plane of Pb ions sandwich-type between two planes of hexagonally arranged I ions. The ionic bonds within I-Pb-I layers are strong while those between adjacent sandwiched layers are weak. [ 29 ] Therefore, the van der Waals interactions between interlayer bonding allows a successfully insertion of different guest molecules. [ 30,31 ] As mentioned above, the PbI 2 (DMSO) complex (DMSO intercalated in layered PbI 2 ) can be successfully converted into perovskite with intramolecular exchange. In this paper, we report that the N -Methyl-2 -pyrrolidone (NMP) molecule also can be intercalated into layered PbI 2 and the PbI 2 (NMP) complex successfully converted into high-quality perovskite with intramolecular exchange. Compared to perovskite fi lms derived from the PbI 2 (DMSO) complex, those derived from the PbI 2 (NMP) complex were found to display a higherquality perovskite layer morphology and higher power conversion effi ciency. While planar perovskite solar cells derived from PbI 2 (DMSO) complex achieved a 15.8% average and 17.1% maximum power conversion effi ciency, those derived from the PbI 2 (NMP) complex achieved a 17.6% average and 19.5% maximum power conversion effi ciency.A previous study has shown that the PbI 2 (DMSO) fi lm has typically been obtained in various steps: [ 9 ] fi rst by synthesizing the PbI 2 (DMSO) 2 complex from a mixture of PbI 2 and DMSO and adding a nonpolar solvent such as toluene; then producing PbI 2 (DMSO) complex from the PbI 2 (DMSO) 2 complex by applying a vacuum oven treatment for 24 h; and fi nally dissolving PbI 2 (DMSO) complexes in DMF and spin-coating this solution on the substrate. Interestingly, we found that the PbI 2 (DMSO) or PbI 2 (NMP) fi lms could be deposited using Of the many materials and manufacturing techniques aimed at fabricating highly effi cient and low-cost photovoltaic cells, hybrid organic-inorganic solar cells that utilize perovskitebased materials as the light-harvesting component have been of great interest as an exciting alternative to third-generation photovo...

Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm active area and 18% over a 1 cm active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.