Toughened Hybrid Electron‐Transporting Interlayers for Efficient and Durable Organic Solar Cells

Electron‐transporting layers (ETLs) are crucial in determining the performance of organic solar cells (OSCs). However, it is challenging to achieve desired efficiency and stability simultaneously for devices based on single‐component ETLs. Here, we demonstrate the application of polyoxometalate (POM)‐doped hybrid ETLs to achieve significantly mitigated efficiency‐stability trade‐off in OSCs. By tailoring the doping behaviors, hybrid ETLs exhibit cascade energy‐level alignment, increased conductivity, improved electrode adhesion, strong thickness tolerance, and suppressed self‐aggregation. These combined merits enable excellent efficiency (20.4%) and outstanding stability (a T 93 / T 92 lifetime of 1500/1000 h under MPP tracking at 40°C/65°C) to be achieved for OSCs. A further elevated efficiency of 20.8% (20.4%, certified) and a T 90 lifetime of 1000 h can also be achieved when PDIN‐EME is used as the new organic component in the hybrid ETL, demonstrating the easy tunability of these hybrid interlayers for more efficient and robust OSCs.