Solar cell is a very new renewable power supply and it still in the development process. Especially with the perovskite-based solar cell (PSC) which in recent year it shows a very high potential of being very efficient power. It has not been the most efficient but the increase or its efficiency percentage is exponentially increasing. In this work, we want to find the most efficient molarity for PbC12. We were using the spin coating and annealing method to make layers of material on top of FTO glass. This method is very simple and easy to use. The PSC structure consists of 6 layers, namely FTO glass, Electron Transfer Material (ETM), Perovskite, Hole Transfer Material (HTM), carbon, and FTO glass. Perovskite on this solar cell is the active layer where this layer will generate electron and hole when it is shined by sunlight. The probability of electron-hole generation will be increased by the more particle of precursors in this active layer. The molarity of precursors of this layer affects the amount of its particle and will raise the performance of the solar cell. From the fabrication results by varying the molarity, it was found that the perovskite-based solar cell with 0.5M of PbC12 is best molarity value with much less PbC12 and MAI needed to make it which save more material, and with the highest result of the performance of the PSC, namely 0.56V Voc, 2.37mAIsc, and 0.33 fill factor.