Multifunctional fluorinated D-PFPAA zwitterions can reduce the number of ionic defects and consolidate Pb–X framework, suppressing ion migration, and form a hydrophobic barrier, significantly improving the power conversion efficiency and stability.

The crystallinity of perovskite films is crucial for the performance and stability of perovskite solar cells (PSCs). Defects usually emerge in grain boundaries, leading to decomposition and non-radiative recombination of PSCs. Here, we present an effective additive engineering strategy to augment the long-term operation and stability of PSCs by doping a molecule with a symmetrical structure and bifunctional passivation, 2,5-thiophene dicarboxylic acid (TDCA), into the precursor solution. It is demonstrated that TDCA coordinates with the perovskite through hydrogen and Pb–O bonding, resulting in significantly enhanced crystallinity and defect passivation such as uncoordinated Pb2+ and I–. Meanwhile, the grain size is increased from 350 nm to about 650 nm for the perovskite, as well as the grain boundaries are reduced, which could inhibit the carrier non-radiative recombination loss. Consequently, the power conversion efficiency of champion PSCs is promoted from 19.31 to 22.78%. Furthermore, the enhanced crystallinity and defect passivation improve the wet-thermal stability of PSCs.

In the organic–inorganic hybrid perovskite absorption layer as the composite center, it is easy to form defects and hinder the performance of solar cells. Here, barbital is introduced into perovskite films for the first time to enhance the photovoltaic performance of the device. It is demonstrated that the carbon‐based functional group in barbital additives can be used as Lewis bases to passivate the Lewis acid defects in perovskite films and promote the transmission of charge through grain boundaries. With the barbital in the perovskite film, the device efficiency is improved from 20.43% to 22.65% with the fill factor enhanced from 0.76 to 0.80. In addition, the perovskite films treated with barbital additive exhibit a lower density of filled trap states (3.07 × 1017 cm−3) in perovskite grain boundaries, and a higher carrier lifetime (428.19 ns). This discovery provides a new tactic for the preparation of a high‐quality perovskite light‐absorbing layer.