Dynamic covalent polymer engineering for stable and self-healing perovskite solar cells

Perovskite films are susceptible to degradation during their service period due to their weak mechanical properties. Acylhydrazone-bonded waterborne polyurethane (Ab-WPU) was employed as dynamic covalent polymer engineering to develop self-healing perovskite solar cells (SHPSCs). Ab-WPU enhances the crystallinity of the perovskite film, passivates the defects of the perovskite film through functional groups, and demonstrates promising flexibility and mild temperature self-healing properties of SHPSCs. The champion efficiency of SHPSCs on rigid and flexible substrates reaches 24.2% and 21.27% respectively. The moisture and heat stability of devices were improved. After 1000 bending cycles, the Ab-WPU-modified flexible device can be restored to an efficiency of over 95% of its original efficiency by heating to 60 °C. This is because the dynamic acylhydrazone bond can be activated to repair perovskite film defects at a mild temperature of 60 °C as evidenced by in situ AFM studies. This strategy provides an effective pathway for dynamic self-healing materials in PSCs under operational conditions. Utilizing acylhydrazone-bonded waterborne polyurethane as a dynamic covalent polymer engineering approach, self-repairing perovskite solar cells demonstrate excellent durability with activation occurring at a relatively low temperature of ∼60 o C.