CH3NH3PbI3 and CH3NH3PbBr3 films deposited by automated spray-pyrolysis for applications in photovoltaic energy

This work aimed to produce CH3NH3PbI3 and CH3NH3PbBr3 films on glass substrates via the automated spray-pyrolysis technique for application as an absorber layer of photovoltaic cells. Their properties were investigated and compared by varying deposition parameters, such as the temperature (250, 300, 350, and 400 °C) and the precursor solution flow (0.25, 0.50, and 0.75 mL/min). Structural characterization by X-ray diffraction revealed the formation of orthorhombic perovskite films. The most adequate temperature and solution flow were 300 °C and 0.50 mL/min for both bromine and iodide films. Morphologically, the films were uniform and free from cracks. CH3NH3PbI3 and CH3NH3PbBr3 films respectively had an optical gap of 1.5 and 2.3 eV, a thickness of 4.56 and 2.35 µm, an absorption coefficient of 0.58x104 and 0.50x104 cm-1, a resistivity of 21.80 and 24.20 kΩ.m, and a figure of merit of 2.66 and 2.07. It was concluded that, between the two compounds, the CH3NH3PbI3 layer has better performance for photovoltaic applications.