Tailoring Defect Passivation for Efficient and Stable Perovskite Solar Cells via an Ionic Liquid Additive
Haoxin Wen, Yixuan Guo, Tianzhou Yin, Zhen Zhang, Shenglin Si, Danxia Huang, Zimin Zhang, Haiting Tan, Hualin Wu, Shaoming Huang
Abstract
As a shining star in the photovoltaic community, perovskite solar cells (PSCs) have been making significant progress in recent years. However, poor long-term operation stability caused by various defects seriously restricts their commercialization process. In this work, a multifunctional ionic liquid passivator, 1-aminoethyl-3-methylimidazolium tetrafluoroborate (AMFB), is incorporated to passivate A +, B 2+, and X – defects in the perovskite absorber and enhance device stability further. It is found that AMFB can cooperate with undercoordinated Pb 2+ and from hydrogen bonds with organic cations and I – ions, leading to a sufficiently passivated perovskite film. Besides, the more suitable energy arrangement and hydrophobicity of the resultant interface contribute to more facilitated carrier transport and durable stability of devices. As a result, the champion power conversion efficiency (PCE) of optimized devices significantly increases from 22.16 to 24.41% with negligible hysteresis, and the large-area devices also boost from 19.86 to 23.24%. Surprisingly, the unpackaged AMFB devices demonstrate excellent robustness against moisture and thermal stresses, maintaining over 90% of their initial PCE after 1500 h of continuous heating at 85 °C and 500 h of aging in moisture air with relative humidity of 70 ± 5%. This work provides an effective and feasible method for improving the performance of PSCs and facilitating their commercialization process.