The interface between the perovskite layer and electron transporting layer has critical effect on the performance and stability of perovskite solar cells (PSCs). The heterogeneity of the interface critically affects the carrier dynamics at the buried interface.
To address this, researchers from Tsinghua University, Xiamen University, Chinese Academy of Sciences (CAS) and National Center for Nanoscience and Technology have developed a bridging molecule, (2-aminoethyl)phosphonic acid (AEP), for the modification of SnO2/perovskite buried interface in n–i–p structure PSCs.
The phosphonic acid group strongly bonds to the SnO2 surface, effectively suppressing the surface carrier traps and leakage current, and making the surface potential more uniform. Meanwhile, the amino group influences the growth of perovskite film, resulting in higher crystallinity, phase purity, and fewer defects.
Furthermore, the bridging molecules facilitate the charge extraction at the interface, as indicated by the femtosecond transient reflection (fs-TR) spectroscopy, leading to champion power conversion efficiency (PCE) of 26.40% (certified 25.98%) for PSCs.
Additionally, the strengthened interface enables improved operational durability of ≈1400 h for the unencapsulated PSCs under ISOS-L-1I protocol.
