Integration of Metal‐Organic Framework With Polymer Electrolyte Enables Efficient and Robust Organic Solar Cells

ABSTRACT Electron transport layers (ETLs) are crucial for reducing the interfacial energy barrier in organic solar cells (OSCs). However, conventional polymer‐based ETLs often suffer from limited conductivity and severe interfacial defects, hindering the improvement in both efficiency and stability. Herein, we develop a hybrid ETL by incorporating a nickel‐based metal‐organic framework (Ni‐MOF) into a polymeric ETL (NDI‐Br). The incorporation of Ni‐MOF introduces abundant Ni centers that coordinate with the bromide anions in NDI‐Br, generating strong interactions that enhance interfacial charge transport and reduce interfacial recombination. OSCs based on the hybrid ETL, NDI‐Br:Ni‐MOF (10:1), exhibit a remarkable efficiency of 20.7%, largely outperforming that (19.1%) of devices based on pristine NDI‐Br. Moreover, the hybrid ETL demonstrates exceptional thickness tolerance (maintaining 17.3% efficiency at 80 nm) and thermal stability with a T 90 lifetime exceeding 1000 h. This work provides a versatile interfacial engineering strategy that can well address the efficiency‐stability trade‐off in OSCs, paving the way for further promoting the practical use of OSCs.