Lead-Halide Perovskite Solar Cells by CH₃NH₃I Dripping on PbI₂–CH₃NH₃I–DMSO Precursor Layer for Planar and Porous Structures Using CuSCN Hole-Transporting Material

The sequential fabrication scheme of the CH₃NH₃PbI₃ layer has been improved to fabricate planar-structure CH₃NH₃PbI₃ perovskite solar cells using CuSCN hole-transporting material (HTM). In the PbI₂ layer fabricated by the spin-coating method, at first, small amounts of CH₃NH₃I (MAI) and DMSO were incorporated as the first-drip precursor layer on a flat TiO₂ layer. On the first-drip precursor layers, an MAI solution was applied by either soaking (MAI-soaking method) or dripping using successive spin coating (MAI-dripping). The morphology and crystal transformations were observed by SEM and XRD, respectively. Using the normal sequential MAI-soaking method, we were unable to fabricate planar CH₃NH₃PbI₃ perovskite solar cells with CuSCN HTM. Using the MAI-dripping method, however, a significant photovoltaic effect has been observed to be planar 2/CH₃NH₃PbI₃ perovskite/CuSCN> solar cells.