Improving the efficiency of perovskite solar cells using modification of CH₃NH₃PbI₃ active layer: the effect of methylammonium iodide loading time

In perovskite (PSK) solar cells, the PSK absorber layer plays a vital role in power conversion efficiency (PCE). In this study, we report on the fabrication of mesoporous PSK solar cells using a two-step spin-coating rout with the structure of glass/FTO/compact TiO₂/mesoporous TiO₂/CH₃NH₃PbI₃ (MAPbI₃)/P3HT/Au. The morphology and crystalline structure of the PSK thin film is controlled by changing the CH₃NH₃I (MAI) loading times (the 20 s, 30 s, 40 s, 60 s) on PbI₂ film. The PSK layers are optimized at different MAI loading times in a two-step process to enhance the PCE of the PSK solar cells. The investigation and comparison of the results show that the solar cell containing the absorber layer prepared by solution loading time of the 40 s is more efficient than the other devices. The champion device shows the open-circuit voltage (V_oc) of 0.97 V, short current density (J_sc) of 19.30 mA/cm², and fill factor (FF) of 0.64, which leads to the best PCE of 12.04%.