Scalable Sheet-to-Sheet-Coating of Double Cation Perovskite Solar Cells based on Green Solvent Systems

Abstract

Hybrid perovskite is a potential next generation solar cell technology owing to photo conversion efficiency (PCE) of 25 % achieved till 2020, which is within less than 10 years of research. Furthermore, low-cost fabrication is possible by relatively low-cost materials and deposition techniques. However, the technology is suffering some issues like efficient techniques for scalable fabrication of perovskite solar cells (PSCs) and the use of conventional toxic solvent in the PSCs fabrication. Such issues are preventing the commercialization of this technology. This work aims at facing this concern by depositing pin hole free, homogenous perovskite absorber layers to fabricate perovskite solar cells, using the two-step sequential blade coating technique and non-volatile or harmless solvent system. The main solvent used for homogenous lead iodide layer is dimethylsulfoxid (DMSO). Further, to improve the film formation, solvent additives such as Ethyleneglycol monobutyl ether (EGBE), surfactant such as L-α-phosphatidylcholine (α-LP) are used. Subsequently, the cation layer is deposited to transform this iodide layer in to the black phase perovskite layer. Cation solution concentration and blade coater parameters such as Blade Gap, Blade Speed, Processing Temperature are optimized for depositing the homogenous absorber layer. The (FAPbI3)0.97(MAPbBr3)0.03 perovskite is formed and used as light absorber layer in the nip configuration planar structure device. An average efficiency of ~17% has been achieved with a Voc = 1.10V and Jsc = 23.5 mA/cm2 with fill factor, FF, of 65%. To see the quality of the perovskite absorber layer and conversion of PbI2 in to the perovskite, homogeneity analysis, UV-Vis Spectroscopy analysis, and XRD analysis are conducted.