Publication date: 8th January 2019
The partial substitution of Pb in the well-known CH₃NH₃PbI₃ perovskite leads to an increase of the absorption range, allowing this kind of perovskites to reach lower bangaps of 1.23 eV.[1] In parallel, the use of CH5N2+ (formamidinium) cation has been reported as a successful approach to improve the thermal stability of this kind of perovskites.[2]
In this work, we show a new way to synthesize FAPb0.5Sn0.5I3 through precursor co-evaporation methods. The characterization of this perovskite was performed by X-Ray Diffraction (XRD), scanning electron microscopy (SEM) and absorbance measurements (UV-Vis). The XRD patterns show the expected perovskite peaks, confirming the formation of the material. From UV-Vis we can conclude the bandgap is 1.22 eV wide. Excellent thickness control is confirmed by cross-sectional SEM measurements. The use of this absorber on a working solar cell with efficiencies up to 13.98%.
We demonstrate the capability to synthesize tin-lead perovskites through co-evaporation, which enables bandgap tuning and presents the opportunity to use them for single-junction and tandem solar cells.