Thermally induced failure mechanisms in double and triple cations perovskite solar cells

The control of the cation composition of formamidinium (FA), methylammonium (MA), and cesium (Cs) has been used to engineer significant improvements in organic–inorganic perovskite solar cells. However, the thermal stability of mixed-cation perovskite solar cells is not fully understood. In this work, we present the results of an experimental study of the stability of double-cation perovskites [(FAPbI3)0.97(MAPbBr3)0.03] [(FAMA)-perovskite solar cells (PSCs)] and triple-cation based-perovskites [Cs0.05(FA0.95MA0.05)0.95Pb(I0.95Br0.05)3] [(CsFAMA)-PSCs] operated between 40 and 60°C. The thermally induced changes in the film microstructure are elucidated via scanning electron microscopy and x-ray diffraction analyses, and these are related to changes in optoelectronic properties, charge transport, and current–voltage characteristics of (FAMA)-PSCs and (CsFAMA)-PSCs. The implications of the observed degradation mechanisms are also discussed for the future development of efficient and stable PSCs.