In this thesis, I investigated how variations in the chemical composition of
perovskite influence the electrical and optical properties of perovskite solar
cells. I prepared several series of cells with different iodide-to-bromide ratios
and implemented the ≫triple-cation≪ method. Additionally, some devices
were treated with an aluminum oxide layer via ALD. Measurements of J–V
characteristics, EQE spectra, photoluminescence (PL), and MPP stability
tests showed that increasing bromide content systematically widened the
band gap and reduced short-circuit current. The ≫triple-cation≪ approach
improved pv parameter reproducibility, but the long-term stability got worse
and reduced the impact of the ALD Al2O3 deposition. The results confirm
that precise tuning of composition is essential for optimizing perovskite cell
performance.
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