Boosting the stability and growth of methylammonium lead bromide perovskites film doped with FA for solar cells

Abstract

In this work, we investigated the lead methylammonium bromide with different contents of formamidinium (0%, 2%, 4%, 6%, 8%, and 10%) deposited by a one-step spin coating method. The effect of FA in MA1-xFAxPbBr3 films was investigated. The crystal structures and morphology, and the optical properties were analysed by X-ray diffraction (XRD), using a scanning electron microscope (SEM) as well as a UV–visible spectrometer, and the surface morphology and optical properties were characterized respectively. From the XRD results, it is found that the crystal structure exhibits 1 crystallographic orientation along the (001) and (002) planes at diffraction angles 2Ɵ = 15.70° and 30.91° respectively. The different layers show perovskite structures with rough surfaces without pinholes although the grain size appearance is different in each case. Optical analysis revealed an increase in the absorbance of the films with FA contents of 6%, 8% and 10% with increasing percentages. For the 2% and 4% contents, the absorbance decreases compared to that of 0% FA. We find that the band gaps are between 1.92 eV and 2.33 eV, the lowest corresponding to the 6% FA layer (1.92 eV). From the results obtained, we can say that the incorporation of FA in MAPbBr3 films is a good candidate for photovoltaic application.For the degradation study, we observed a decrease in the different peaks from XRD and absorption of the samples after 4 weeks in the ambient environment. This decrease is attenuated for some films such as thin films with 0% FA, 4% FA and 8% FA. The different morphological surfaces also experienced degradation. In general, we can say that some films are more or less resistant to the elements of the ambient atmosphere.