Enhancing the Stability of Perovskite Solar Cells with a Multilayer Thin-Film Barrier

The long-term stability of perovskite solar cells (PSCs) remains a big challenge for the commercialization of this emerging photovoltaic technique. The protection of PSCs with a robust barrier/ encapsulation could largely extend their life span. Here, we develop a multilayer thin-film barrier with the architecture of parylene/MgF2/Al2O3 as thin-film encapsulation for PSCs. The water vapor transmission rate of the multiple thin-film barriers can reach a very low value of 1 x 10-4 g m-2 d-1, comparable to that of the thin-film encapsulation in electronic packaging, making the multilayer thin-film barrier robust to block the ingress of H2O/O2 and outward leakage of perovskite decomposition byproducts. As a result, the light and thermal stability of perovskite films and the operational stability of PSCs are effectively improved with multiple thin-film barriers; especially, the encapsulated devices show negligible degradation after operation under the maximum power point tracking under 1sun illumination for 1000 h. In addition, the devices can retain 96% of their initial PCEs on average after aging for 100 h in an 85 degrees C-85%RH damp heat test.