Organic solar cells with 21% efficiency enabled by a hybrid interfacial layer with dual-component synergy

The cathode interfacial layer (CIL) critically influences electron extraction and charge recombination, thereby playing a pivotal role in organic solar cells (OSCs). However, most state-of-the-art CILs are constrained by limited conductivity, high recombination and poor morphology, which collectively hinder device efficiency and stability. Here we report an inorganic–organic hybrid CIL (AZnO-F3N), developed by a dual-component synergy strategy, which integrates organic material PNDIT-F3N with two-dimensional amorphous zinc oxide. This design leverages the synergistic interactions between two-dimensional amorphous zinc oxide and PNDIT-F3N, resulting in reduced interfacial defect, enhanced conductivity and improved film uniformity. OSCs incorporating the AZnO-F3N CIL exhibit more efficient charge extraction and transport, along with reduced recombination. Consequently, a D18:L8-BO-based binary OSC achieves an efficiency of 20.6%. The introduction of BTP-eC9 as the third component further elevates the efficiency to 21.0% (certified as 20.8%). Moreover, the CIL demonstrates versatility across various active layers, thick-film configuration and flexible devices, underscoring its great potential to advance OSC technology.