Multifunctional and multi-site interfacial buffer layer for efficient and stable perovskite solar cells

Perovskite solar cells (PSCs) have achieved significant success in power conversion efficiency (PCE) and stability. However, interfacial recombination and film defects still hinder the improvement of PSCs efficiency. In this study, we propose a novel interfacial buffer layer material called Ethyl p-nitrobenzoate (EPN) to enhance device performance and stability. Our results demonstrate that introducing EPN improves the film's quality, reduces defect density, relieves interfacial stress, and significantly suppresses nonradiative recombination at the interface. Density functional theory (DFT) calculations confirm that EPN can effectively passivate defects in the perovskite and SnO2 films due to its multifunctionality. Finally, we achieved a high PCE of 23.16% for the target device while significantly enhancing device stability compared to the control. This work provides new insights into the development of multifunctional multi-site interfacial buffer layers for high-performance PSCs.