In the thesis, we explored the impact of varying the ratio of cesium (Cs) and formamidinium (FA) on the bandgap of FACs perovskite solar cells, and how these changes affect their optical and electrical properties. The ability to tune the bandgap means that perovskites can be adjusted for various applications, such as different types of photovoltaic cells or light-emitting diodes. We fabricated perovskite solar cells with 4 compositions with varying proportions of Cs and FA. For each composition, we created 48 cells (8 substrates). We measured the I-V characteristics of the cells and calculated basic parameters such as open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE). The best cells achieved an efficiency of over 19% and a fill factor of over 75%. From measurements of external quantum efficiency (EQE), photoluminescence (PL), and transmission (T), we found that as the proportion of Cs increases, so does the bandgap of the perovskite. Finally, we conducted maximum power point tracking (MPPT), where all the cells showed good stability without degradation during 50 minutes of tracking.
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