Defects and energy level mismatches at the buried interface between the ESL and the perovskite have long limited both the efficiency and stability of perovskite solar cells. Although dipolar molecular modification is an effective strategy for interface optimization, the systematic relationship between the EDG/EWG ratio and interfacial properties has remained unclear.
Here, we classify dipolar molecules into three types: EWG-rich, balanced, and EDG-rich, and using L-aspartic acid (AA), 4-aminobutyric acid (ABA), and L-2,4-diaminobutyric acid (DBA) as model systems. Through experiments and theoretical calculations, we demonstrate that the key bottleneck limiting buried interface performance lies on the perovskite side, rather than the ESL side.
The EDG-rich DBA modification achieves the most efficient defect passivation, promotes high-quality perovskite film growth, enhances the interfacial electric field, and accelerates electron extraction and transport. As a result, the corresponding devices show high photovoltaic performance and retain higher efficiency after 30 days of ambient storage without encapsulation, demonstrating excellent long-term stability.
This work establishes asymmetric molecular engineering dominated by the EDG/EWG ratio as a core design principle for buried interface optimization, offering a clear and practical route toward more efficient and stable perovskite solar cells. The work entitled “Electron-donor/-acceptor ratio-guided molecular engineering for buried interface optimization in n-i-p perovskite solar cells” was published in Energy Materials on April 7, 2026.
DOI：10.20517/energymater.2025.183