The effect of bromine on the mixed halide perovskite

Using the sequential deposition method, we introduce a mix halide perovskite solar cell. The Pb and I are provided by PbI2 precursor and Br is delivered by Methyl ammonium bromide (MABr) precursor. The effect of Br on the open circuit voltage (VOC) and the band gap is studied. Addition of Br to the iodide-based perovskite improves its surface morphology and widens the perovskite bandgap, and hence increases the resulting solar cell VOC. However, pinholes created in the perovskite layer due to addition Br results in a dramatically reduced short circuit current density (JSC). The UV-Vis spectroscopy, indicating two optical bandgaps, confirms a two-phase perovskite structure is produced.