Investigation of the stability and efficiency of MA-doped FAPbBr3 thin films for solar cells

Abstract

Perovskite solar cells are becoming one of the most attractive solar cell technologies. They have achieved a power conversion efficiency (PCE) of 22.7% in 10 years. They show excellent efficiency with low stability. The degradation process of perovskite devices has been associated with mobile ion migration. The MAPbBr3 perovskite materials are significantly more stable under ambient conditions but have a larger band gap (2.3 eV) than the FAPbBr3 perovskite materials, which have an interesting band gap (1.6 eV).Here we use a mixture of MAPbBr3 and FAPbBr3 materials with a high proportion of FAPbBr3 to obtain a stable active layer with a good band gap by the one-step spin-coating method on the FTO. The X-ray diffraction (XRD) results show four peaks for all five samples, with the main one located at 26.84° for the (111) crystallographic plane. This (111) plane gives the preferred crystallographic orientation of the thin films we prepared. The surface images of the films show that the surfaces are mainly well coated with varying grain sizes depending on the layer. The absorption coefficient of the 10% MA is higher compared to the others films, The band gaps of the x% MA: FAPbBr3 films are from 2.39eV to 2.68eV with the lowest corresponding to the 10% MA doped layer. The degradation study revealed that the absorption of aged films decreased after 4 weeks of exposure to the ambient environment.for 10% of MA-doped FAPbBr3. We found intermediate properties as expected, notably the stability as well as the band gap whose value is 2.40 eV. Indeed, the degradation process of the prepared thin film is slower than that of pure FAPbBr3. The absorption of the mixite MA and FA is good to be used as an absorber layer for solar cells.