Direct synthesis of PbI2 precursor film via magnetic field- and additive-assisted electrodeposition for stable carbon-based perovskite solar cells

Electrodeposition is one of the most established techniques for large-scale coating in a wide range of applications. Nevertheless, applying the technique for the fabrication of perovskite solar cell has only found limited success, plausibly due to the morphology issues, such as inhomogeneous distribution of the grain size and even the peeling off of the coated film. In this study, the electrodeposition approach was significantly revised to address the morphology issues and enable high-performance perovskite solar cell. By preparing the PbI2 precursor layer using magnetic-field assisted electrodeposition with polyvinyl alcohol (PVA) as an additive and the total charge of 1.2 C/cm2, the resulting perovskite crystal layer was stably deposited on the supporting substrate and showed good contact with adjacent layers. When assembled into the device using carbon back contact under ambient air at 50-75% relative humidity, the power conversion efficiencies (PCEs) of 7.50% and 5.17% were obtained for the active areas of 0.051 cm2 and 1 cm2, respectively. The device showed outstanding photocurrent density of 22.56 mA/cm2 for 0.051 cm2 active area. Interestingly, the unencapsulated device revealed robust performance that could maintain stability at least 99% of the initial PCE after 500 h. This study could offer a facile and scalable approach for direct PbI2 film preparation based on the electrodeposition-based technique.