Dual Cross‐Linked Functional Layers for Stable and Efficient Inverted Perovskite Solar Cells

The operational stability of p–i–n perovskite solar cells (PSCs) is dramatically subjected to the quality of the perovskite light harvester and the interface layer atop the perovskite. Herein, a dual crosslinked functional layer strategy of using the versatile polydimethylsiloxane as an additive both in the perovskite layer and in phenyl‐C61‐butyric acid methyl ester interface layer, to improve the device tolerance against light, thermal, humidity, and bending stress, is reported. As a result, a promising power conversion efficiency of 21.6% (stabilized at 21.3%) for nickel oxide‐based p–i–n PSCs is achieved. In addition, the unencapsulated devices maintain 97% of their initial efficiencies after continuous operation under 1 sun equivalent illumination at 60 °C with maximum power point tracking for 1000 h and 80% of their initial efficiencies exposed in ambient air for 500 h. The application of the aforementioned strategy in the flexible device also improves the bending mechanical stability, of which the corresponding flexible devices maintain 85% of their initial efficiencies after 1000 cycles at a radius of 8 mm.