Parylene Capping for Prolonged Stability of Perovskite Solar Cells

The effect of Parylene capping on perovskite solar cells has been tested by its deposition on top of FACs perovskite devices, already capped with 30‐nm‐thick Al 2 O 3 , in three different thicknesses: 2, 5, and 15 μm. The cells were tested against ingress of water, in damp‐heat chamber and long‐term maximum power point operation. Devices immersed in water and tested in the damp‐heat chamber were regularly measured under a sun simulator to monitor their performance, in addition to visual comparison. In all tests, Parylene‐capped cells outperformed the reference without Parylene, clearly demonstrating the beneficial effect of Parylene. In the long‐term stability test in air without additional encapsulant, the perovskite solar cell's t 80 lifetime (time till 80% of initial performance) was tripled in the case of 5‐μm‐thick Parylene.