Optical characteristics and solar cell performance of (MAPbBr3)x ((MACl)0.28FA0.98Cs0.02PbI3)1−x with various composition ratios

Perovskite solar cells were prepared using (MAPbBr3)x ((MACl)0.28FA0.98Cs0.02PbI3)1−x, (x = 0, 0.05, and 0.07) perovskite layers. The effect of the MAPbBr3 amount on the formed phases and lattice parameters of the formed perovskite films was explored using the X-ray diffraction technique. The addition of MAPbBr3 to the formed films resulted in an increase in the grain size from 52 to 68 nm. A method that accounts for the interference phenomenon was applied for retrieving the optical constants from the interference fringes of the reflectance spectra of the different samples. The direct optical band gap was decreased from 1.45 eV to a minimum value of 1.34 eV as MAPbBr3 was added to the perovskite film. In the visible range, the refractive index value of the film with 5