Minimizing vacancy defects with Eu passivation strategy to enable highly efficient perovskite photovoltaics

• Published in: Applied surface science 2025-03, Vol.684, Article 161922
• Main Authors: Sun, Ping-Ping, Shi, Yutong, Wang, Gaoyin, Deng, Ken, Wu, Jinfu, Zeng, Chaoyuan, Chi, Weijie
• Format: Article
• Language: English
• Subjects: Activation energy barrier; Defect formation energy; Defect passivation; Huang–Rhys factor; Ion migration; Perovskites stability
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.161922

The pivotal role of Eu passivation is found in finely reducing the bandgap, enhancing activation barriers, and improving the stability of perovskites. The I and Pb ion migration path along the Eu passivated VI, VPb, VI-Pb surfaces from the left to right. [Display omitted] •Eu can decrease the defect formation energies of perovskite.•Eu passivation will improve the activation energy barriers for ion migrations.•I and Pb ions migration was prevented on the defected surfaces.•The introduction of Eu will suppress hysteresis effect and improve the stability. The intrinsic ionic nature of metal halide perovskites facilitates the formation of abundant defects at grain boundaries (GBs) and surfaces, consequently diminishing the stability and photovoltaic performance of perovskite solar cells (PSCs). Due to the low formation energies and instability of Pb-I bonds, iodine (I) and lead (Pb) vacancies are prevalent high-density point defects. In this study, we explore the use of europium (Eu) as a novel passivator to concurrently address I and Pb vacancies through first-principles calculations. Our results demonstrate that Eu significantly lowers the defect formation energies and adjusts the bandgap, enlarged by vacancy defects, to align with the ideal Shockley-Queisser limit, indicating a strong potential for achieving high power conversion efficiency (PCE). Furthermore, Eu passivation markedly increases the activation energy barriers for ion migration, resulting in substantially reduced migration rates. This suggests a minimal likelihood of I and Pb ion migration on defected surfaces, underscoring Eu’s potential to mitigate hysteresis effects and enhance stability. This work advances our understanding of the passivation effects of rare earth elements and establishes a foundation for designing highly effective passivation strategies to achieve stable and efficient PSCs.