Multidentate Polymer-Stabilized Buried Interface for Efficient Planar Perovskite Solar Cells

Buried interface engineering is crucial to improve the performance and stability of perovskite solar cells (PSCs). Although coordination materials have been widely used for buried interface modification, they are generally engineered on one surface of the interface through monodentate or bidentate molecules. Here, we propose that a multidentate polymer, sodium alginate (SA), acts with both surfaces via numerous C═O groups to reinforce buried interfaces. SA effectively reduces buried interface defects, adjusts the energy level alignment, and refines carrier dynamics. Notably, it also induces the growth of a perovskite film that is less tensile stressed and free of voids. Consequently, the champion device efficiency after SA treatment increased from 23.05% to 24.98%, along with significant improvements in both light and thermal stability. This work offers insights into efficiency and stability improvement from the perspective of multidentate polymer anchoring.