PbI6 Octahedra Stabilization Strategy Based on π‐π Stacking Small Molecule Toward Highly Efficient and Stable Perovskite Solar Cells

• Published in: Advanced energy materials 2023-03, Vol.13 (11), p.n/a
• Main Authors: Wang, Xianzhao, Liu, Dachang, Liu, Ruichen, Du, Xiaofan, Zhang, Bingqian, Sun, Xiuhong, Chen, Chen, Li, Zhipeng, Zhao, Qiangqiang, Shao, Zhipeng, Wang, Xiao, Cui, Guanglei, Pang, Shuping
• Format: Article
• Language: English
• Subjects: Amides; Benzamide; Charge efficiency; Charge injection; Crystal defects; Diffusion layers; Diffusion length; Efficiency; Energy conversion efficiency; energy levels; Grain boundaries; Iodine; iodine loss; ion migration; Perovskites; Photovoltaic cells; Solar cells; stability; Stabilization; Stacking; π‐π stacking
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202203635

The unavoidable iodine loss in the perovskite layer is closely related to carrier non‐radiative and device degradation. During the post‐annealing process, the fragile PbI bond is easy to break, leading to the formation of iodine vacancies and inducing stress‐driven structure collapse. Herein, a PbI6 octahedra stabilization strategy via building robust grain boundary modification networks is developed. The introduction of conjugated structure into amides can significantly enhance their anchoring ability with PbI units, while the π–π stacking effect of benzamide enables a passivation network with polymer‐like effect. This is well evidenced by the excellent properties in eliminated iodine loss and stabilized perovskite lattice. Therefore, benzamide modification not only transform the perovskite films from n‐type to p‐type by suppressing the iodine vacancy‐doping effect, but also reduces defect density, ultimately bringing the perovskite layer longer carrier diffusion length and better charge injection efficiency. Finally, the benzamide modified devices realize both high power conversion efficiency of 24.78% and excellent operating stability. Of particular note, the module efficiency with 14 cm2 active area is over 21%. To avoid the iodine loss in perovskite film, this work provides a novel strategy to govern the PbI6 framework based on a “polymer like” molecule, benzamide. The modified perovskite solar cells (PSCs) show well‐tuned level structure and low defect density. And both the performance and long‐term stability of PSCs are significantly improved.