Here, we report important findings regarding underestimated parameters for the synthesis and fabrication of high-performance perovskite solar cells. These parameters include the effect of Fluorine-doped Tin Oxide (FTO) etching, FTO cleaning, number of spin-coated compact TiO2 (c- TiO2) and mesoporous TiO2 (m--TiO2)and aging time before Ag deposition. Our results demonstrated that etching of FTO substrate with Zn/ HCl is an essential step and has a major effect on the solar cell’s open circuit voltage (Voc), fill factor (FF) and power conversion efficiency (PCE). Furthermore, we systematically demonstrate that the widely used protocols for cleaning the FTO substrate were not sufficient for complete cleaning. In addition, the optimum number of spin coated layers of compact and mesoporous TiO2 precursors was investigated. Consequently, we demonstrate that using these optimized device fabrication procedures, a high efficiency of 17.96% for 6 mol% Co3+-doped TiO2 solar cells can be obtained in comparison to 16.98% for pristine TiO2-based cells. Such cells are particularly important for wearable applications that require a small area and a high energy