Enhancing Long-Term Thermal Stability of Non-Fullerene Organic Solar Cells Using Self-Assembly Amphiphilic Dendritic Block Copolymer Interlayers

Herein, interfacial engineering is demonstrated to improve the thermal stability of non-fullerene bulk-heterojunction (BHJ) OPVs to a practical level. An amphiphilic dendritic block copolymer (DBC) is developed through a facile coupling method and employed as the surface modifier of ZnO electron-transporting layer in inverted OPVs. Besides showing distinct self-assembly behavior, the synthesized DBC possesses high compatibility with plasmonic gold nanoparticles (NPs) due to the constituent malonamide and ethylene oxide units. The hybrid DBC@AuNPs interlayer is shown to improve device's performance from 14.0% to 15.4% because it enables better energy-level alignment and improves interfacial compatibility at the ZnO/BHJ interface. Moreover, the DBC@AuNPs interlayer not only improves the interfacial thermal stability at the ZnO/BHJ interface but also endows a more ideal BHJ morphology with an enhanced thermal robustness. The derived device reserves 77% of initial PCE after thermal aging at 65 °C for 3000 h and yields an extended T₈₀ lifetime of >1100 h when stored at a constant thermal condition at 65 °C, outperforming the control device. Finally, the device is evaluated to possess a T₈₀ lifetime of over 1.79 years at room temperature (298 K) when stored in an inert condition, showing great potential for commercialization.