The research of inorganic-organic hybrid lead halide perovskite solar cells have been a center topic on photovoltaic field. Several aspects that make perovskite solar cells competitive to conventional silicon solar cells are high performance, ease of fabrication, tunability of bandgap, and low manufacturing cost. One of the widely used fabrication process in perovskite solar cell is via solution process. However, the major concern in solution process is the reproducibility of the solar cells. Here, we studied the effects of how precursor solutions affected the device performance. By using Dynamic Light Scattering (DLS), we have indicated that the triple-cation lead mixed halide perovskite have a tendency to aggregate into two aggregates as the precursor solution further aged, namely FA-rich and Cs-rich: Whereas in single cation lead halide perovskite, the existence of aggregates does not affect the device performance. In addition, we have showed the bandgap tuning of triple-cation lead mixed halide perovskite in order to create a wide-bandgap perovskite solar cells. With optimization via halide intercalation, we have point out the composition that is suitable for top-cells tandem solar cells. A preliminary device efficiency result was reported. Despite the successful device fabrication, further efficiency enhancement and device stability must be researched.