In Situ Nbo X as an Efficient Interfacial Layer on Sno2 Electron-Transport Layer for High‐Performance Flexible Perovskite Solar Cells

The long‐term environmental and mechanical stability issue of perovskite solar cells (PSCs) hinders their commercialization. The interface defects affect device stability and power conversion efficiency (PCE), which is derived from the carrier recombination and mechanical properties between adjacent layers. Herein, we report an in situ formed NbOx passivation layer at the interface of the SnO2/perovskite layer with the micro island bulge nanostructures. This approach reduces nonradiative recombination losses and optimized band alignment. As a result, the open‐circuit voltage from 1.13 to 1.17 V, leading to a PCE of 23.64% (active area of 0.09 cm2). Additionally, the PSCs demonstrated exceptional stability, retaining over 80% of their initial efficiencies after 2,000 h of exposure to ambient atmosphere without encapsulation. Furthermore, the solution-processed and low-temperature available interfacial layer was applied to flexible perovskite solar cell (F-PSCs), achieving a PCE of 21.86%. Again, it maintains more than 74.94% of their initial values after 10,000 ultimate bending cycles.