Doped methylammonium lead iodide (MAPbI3) solar cells with cesium (Cs) (MA1-xCsxPbI3, x=0, 0.03, 0.05, 0.1) thin films were prepared with and without chlorobenzene (CB). The change in the crystallinity of the formed films upon doping with Cs was studied using an X–Ray diffraction technique. The Rietveld refinement method applying MADU software was used to reveal the effect of Cs and CB on the lattice parameters, crystallite size, strain and dislocation of the formed films. CB reduced the number of pinholes and the grain size in the formed films as compared with the corresponding films prepared without CB. The UV-Vis-NIR spectroscopy technique was used to investigate the transmittance, reflectance and absorbance spectra for Cs doped MAPbI3 with and without CB. At 500 nm, the MAPbI3 thin film prepared without CB has the highest transmittance as compared with other thin films. The reflectance of the Cs doped samples prepared with CB is higher than for the samples prepared without CB. In the visible range, the absorbance has the highest values in 5% Cs (without CB) and 10% Cs (with CB) doped samples. The changes in the refractive index depend on the amount of Cs doping and the samples prepared with and without CB. The direct optical band gap of all films is affected by the crystallite size and the formed localized state created inside the bend. Samples prepared with CB have a higher optical conductivity than the corresponding samples prepared without CB. The influence of Cs doping and CB addition on the photoluminescence (PL) emitted spectra was studied using a PL set-up with a laser source of 532 nm.
Optical response of mixed methylammonium lead iodide and formamidinium tin iodide perovskite thin films
