Enhancing the efficiency and stability of perovskite solar cells using ALD-Al2O3 as an electron transport layer buffer

Abstract

Perovskite solar cells (PSCs) have achieved remarkable efficiency gains in recent years, yet their practical performance is still limited by interfacial defects and stability issues. Here, we employ atomic layer deposition (ALD) to introduce an ultrathin and conformal Al₂O₃ film as a buffer layer at the electron transport layer (ETL)/electrode interface in both n–i–p and p–i–n PSC architectures. The precisely controlled ALD-Al₂O₃ layer effectively passivates interfacial defects, reduces surface roughness, and facilitates carrier extraction. As a result, the PCE of n–i–p devices increased to 20.2% and 13.24% when using Au and carbon electrodes, respectively, while p–i–n devices achieved a PCE of 18.91% by replacing BCP with ALD-Al₂O₃. Beyond efficiency enhancement, the ALD-Al₂O₃ buffer layer also improved operational stability, demonstrating its multifunctional role in both defect passivation and interface regulation. This work highlights the use of ALD-Al₂O₃ as a universal and scalable interfacial modification strategy, offering a new pathway to simultaneously boost the efficiency and durability of PSCs.