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Abstract The optimal selection of alkyl chains and halogen ions in ammonium salts for addressing specific defect types in perovskite films remains unclear, although ammonium salts emerged as a promising strategy to enhance the performance of perovskite solar cells (PSCs). Herein, four ammonium salts are introduced with different alkyl chain types and halogen ions to passivate perovskite films. Branched‐alkyl chain ammonium salts exhibited superior passivation effects compared to linear‐alkyl chain salts, with the alkyl chain structure having a more significant impact on device performance than the halogen ion component. In addition, DFT calculations are performed to investigate which defect types in perovskite films are most effectively passivated by different alkyl chain types and halogen ions in ammonium salts. Branched‐alkyl chain ammonium salts demonstrated superior passivation effects on V_Pband V_FAdefects in perovskite films compared to linear‐alkyl chain salts, while exhibiting similar passivation effects for V_Idefects. PSCs passivated with tert‐OAI achieved an impressive efficiency of 25.49%, with a V_ocof 1.19 V, a J_scof 25.40 mA cm⁻², and an FF of 84.34%. This work highlights a targeted ammonium salt passivation strategy tailored to address different defect types in perovskite films, accounting for variations in perovskite composition and fabrication environments. 

Although water is considered essential to life and an important natural resource, disadvantaged communities, such as low-income and minority communities, are disproportionately burdened by lead exposure in drinking water. In this paper, we highlight case studies that have received national press coverage as well as recent examples of community lead poisoning hazards that are still ongoing across various regions of the US. We show through these three case studies of Flint, Michigan, Washington, D.C., and Birmingham, Alabama, that the severity and frequency of this pervasive public health problem are highly concentrated in minority and low-income populations, and thus they bear the brunt of the socio-economic impacts. We identify the use of sensors to improve detection of hazardous materials and decrease inequities in drinking water contamination. To address water-related equity issues, we call for a sustainable community capacity approach that consists of shared governance between those who live in a community and stakeholders, such as businesses and health services, who have vested interests in it. We conclude by highlighting ways that a community could build collective social capital, safeguarding its environment from lead poisoning through health literacy education. Promoting water literacy is highly significant since water knowledge is crucial towards achieving water sustainability and equity.