Reinforcement of Cathode Interface Using a Dipolar Small Molecule for Enhancing Operational Stability of Perovskite Solar Cells

Perovskite solar cells (PSCs) with inverted structures have garnered considerable attention in photovoltaic research due to their high scalability and efficiency. However, challenges at the interface between the electron transport layer (ETL) and cathode, including energy level mismatch, halide ion migration, and metal degradation, limit performance and stability. In this study, we introduce a quinoxaline-based high-dipole material (MQPPO) as a novel cathode interlayer (CIL) for p-i-n structures. MQPPO improves energy level alignment, charge extraction, and interfacial stability through its strong dipole moment and hydrophobic properties. The superior performance of MQPPO-incorporated devices was reflected in their power conversion efficiency (PCE), achieving 21.65% under 1 sun illumination. Additionally, MQPPO-based PSCs demonstrated exceptional long-term stability, maintaining over 80% of their initial efficiency after 1440 h. These results demonstrate that MQPPO is an effective CIL material for high-performance and stable PSCs, advancing their potential for sustainable energy technologies.