Phytate modifies the hole transport layer and assists in blade coating to prepare efficient perovskite solar cells

The blade coating method is considered a promising large-scale manufacturing technology for its economy and applicability to the large-scale roll-to-roll process. However, the performance of devices currently produced by doctor blade coating remains lagging behind that of spin-on devices for their low film quality and inadequate coverage. In this study, an inter-layer of phytic acid sodium (PAS) was introduced between the NiO x hole transporting layer (HTL) and the perovskite absorption layer to enhance the film quality and coverage. By regulating the flow and the drying process of the one-step perovskite solution in dimethyl sulfoxide (DMSO) and gamma-butyrolactone (GBL) solvent, a complete high-quality perovskite film was formed, and the domain size considerably increased from about 50 µm to 100–200 µm. According to the lower VB value of −5.3 eV achieved by the PAS modified NiO x film, the device with PAS inter-layer could more effectively fit energy level and extract holes. Moreover, PAS also promoted a better contact between NiO x layer and the perovskite layer; thus, the filling factor (FF) was up-regulated from 52.96% to 60.82% by enhancing the interfacial properties. Lastly, the power conversion efficiency (PCE) of the perovskite solar cell device fabricated by doctor blade coating in the atmospheric environment was up-regulated from 10.07% to 13.19% (aperture, 1 cm 2 ). The finding of this study can guide the preparation of perovskite films by doctor blade coating.