Thermal treatment of the cell samples after dc sputtering of the Au electrodes enhanced the reproducibility of the perovskite cell efficiencies because the thermal annealing induced the strong adhesion between each layer of the cells. The thermal annealing at 100 °C for 10 min in dry air atmosphere using the Au/HTL(hole transport layer)/dye (single-step process)/m-TiO₂/c-TiO₂/FTO/glass samples showed the highest efficiency of approximately 8.57 ± 0.26% with a reproducibility of the efficiency. The solar cells with perovskite dyes which were deposited and annealed in N₂ atmosphere using the two-step process (deposition using a low and high concentrated-CH₃NH₃I solution) exhibited more enhanced efficiency and reproducibility (13.13 ± 0.05%) than those (8.57 ± 0.26%) of single-step process.