Summary Additive engineering has become increasingly important for making high-quality perovskite solar cells (PSCs), with a recent example involving acid during fabrication of cesium-based perovskites. Lately, it has been suggested that this process would introduce dimethylammonium ((CH 3 ) 2 NH 2 + , DMA + ) through hydrolysis of the organic solvent. However, material composition of the hydrolyzed product and its effect on the device performance remain to be understood. Here, we present an in-depth investigation of the hydrolysis-derived material (i.e., DMAPbI 3 ) and detailed analysis of its role in producing high-quality PSCs. By varying the ratio of CsI/DMAPbI 3 in the precursor, we achieve high-quality Cs x DMA 1-x PbI 3 perovskite films with uniform morphology, low density of trap states, and good stability, leading to optimized power conversion efficiency up to 14.3%, with over 85% of the initial efficiency retained after ∼20 days in air without encapsulation. Our findings offer new insights into producing high-quality Cs-based perovskite materials.

Inorganic CsPbI3 perovskites have shown promising potential for achieving all-inorganic photovoltaic (PV) devices. However, the black perovskite polymorph (α-phase) of CsPbI3 easily converts into yellow colour (δ-phase) in an ambient environment and it is only stable at high temperature (above 320 °C), which limits its practical application. Here we tailor the three-dimensional CsPbI3 perovskite into quasi-two-dimension through adding a large radius cation phenylethylammonium (PEA+). The incorporation of PEA+ into the CsPbI3 perovskite significantly improves the film morphology as well as the phase stability. An optimal CsxPEA1-xPbI3 perovskite film remains stable in the α-phase from room temperature to 250 °C in air and yields a power conversion efficiency of 5.7% for its solar device. The concept of using large radius cations in the 3D perovskite system provides a new perspective to further enhance the phase stability while retaining the device performance.

Environmental pollution is an important factor that harms public health, and environmental regulation is the policy instrument to govern pollution, so what impact does environmental regulation have on the public health? What are the mechanisms? To answer these questions, this paper constructs ologit model and uses China General Social Survey data for empirical analysis. The study found first that environmental regulation has a significant effect on improving the health level of residents, and this effect has been increasing with the passage of time. Second, the impact of environmental regulation on residents' health is different among residents with different characteristics. Specifically, the positive impact of environmental regulation on residents' health is stronger among residents with at least a university degree, residents with urban-registered residences, and residents living in economically developed areas. Third, the mechanism analysis found that environmental regulation can improve residents' health by reducing pollutant emissions and improving environmental quality. Finally, by introducing a cost benefit model, it was found that environmental regulation has a significant effect on improving the welfare level of individual residents and society as a whole. Hence, Environmental regulation is an effective means to improve residents' health, but when implementing environmental regulation, we should also pay attention to its negative impact on residents' employment and income.