In this thesis, we investigated the influence of MAPbBr3 added to a basic FACs perovskite composition on the PV parameters of a solar cell, and on their long-term and temperature stability. Methylammonium-free (MA) perovskite solar cells have recently gained popularity due to their higher thermal stability. Due to its volatility at relatively low temperatures, MA causes problems in the encapsulation process and has a negative impact on the long-term stability of the solar cells. On the other hand, the addition of MA to the perovskite composition allows for easier film formation, resulting in a higher PCE. As the amount of MA increases, the energy gap also increases, which can be exploited for the fabrication of tandem cells in combination with silicon. All of these usefull properties of MA make it worth investigating further to see to what extent they outweigh its disadvantages.
For the purpose of this thesis, two batches of cells have been fabricated. In the first one, the influence of two different anti-solvents used in the spin coating process of perovskite was investigated, and in the second one the influence of different amounts of MAPbBr3 added on the cell properties was determined. Different measurement systems were used for cell characterisation. For each composition, we fabricated highly efficient devices with power conversion efficiencies above 19%. On average, the highest PCE and FF were obtained in cells with 0% and 6% quantity of MAPbBr3, although some cells of other two compositions also mediate PCE and FF above 19% and 75% respectively. The results of the I-V measurements also showed that VOC increases while JSC decreases with the addition of MAPbBr3. From the results of EQE, photoluminescence and transmission measurements, we confirmed that the energy gap widens with increasing MAPbBr3 content. The bandgap of FACs with 10% MAPbBr3 is 1.69 eV, which is otpimal for perovskite/Si tandems. From the Sun-VOC measurements, we determined the ideality factor n. For the final measurements we subjected the cells to high temperature and maximum power point (MPP) tracking. We found that cells with higher MAPbBr3 content degrade more rapidly, especially when the content is 10%. In other cases this is not so pronounced, but there is still a trend towards a decrease in PV parameters. In the master thesis, we have therefore determined that despite overall good results, MA-free FACs is still the best composition due to its better thermal stability.
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