Synergistic Defect Passivation and Ion Migration Suppression in Wide-Bandgap Perovskite Solar Cells Using Carbonyl-Rich Cadmium Additives

In recent years, wide-bandgap perovskite solar cells have attracted significant attention for their potential in tandem photovoltaic applications. However, their development suffers from severe open-circuit voltage loss caused by photoinduced phase segregation and nonradiative recombination. To address these challenges, we introduced cadmium acetylacetonate additives, rich in carbonyl groups and cadmium atoms, into the perovskite precursor solution. These additives effectively passivate defects within the perovskite film and enhance carrier transport, leading to more efficient and stable wide-bandgap solar cells. The carbonyl groups interact with FA+ and undercoordinated lead ions to eliminate defects and enhance structural stability, while the cadmium atoms inhibit iodine ion migration through strong ionic interactions. These functional groups synergistically suppress nonradiative recombination losses and optimize energy levels alignment. As a result, the champion device (Eg = 1.67 eV) treated with cadmium acetylacetonate achieves a power conversion efficiency of 18.25% and retains 92% of its initial efficiency after 1392 h of storage under a nitrogen atmosphere. This work offers new insights into the design of multifunctional additive strategies for advancing perovskite photovoltaics.