Self-control problems constitute a potential explanation for the under-investment in preventive health in low-income countries. Behavioral economics offers a tool to solve such problems: commitment devices. We conduct a field experiment to evaluate the effectiveness of different types of theoretically-motivated commitment contracts in increasing preventive doctor visits by hypertensive patients in rural India. Despite achieving high take-up of such contracts in some treatment arms, we find no effects on actual doctor visits or individual health outcomes. A substantial number of individuals pay for commitment but fail to follow through on the doctor visit, losing money without experiencing health benefits. We develop and structurally estimate a pre-specified model of consumer behavior under present bias with varying levels of naivete. The results are consistent with a large share of individuals being partially naive about their own self-control problems: sophisticated enough to demand some commitment, but overly optimistic about whether a given level of commitment is sufficiently strong to be effective. The results suggest that commitment devices may in practice be welfare diminishing, at least in some contexts, and serve as a cautionary tale about their role in health care.

The organic–inorganic Sn–Pb mixed perovskite has achieved great progress during the last 10 years and is considered as one of the most promising low‐bandgap photovoltaic materials. It has lower toxicity, outstanding optoelectrical properties, and achieved remarkable performance. However, there are still plenty of challenges in controlling the morphology, crystallinity, and defects of the Sn–Pb mixed perovskite film because of the inferior chemical stability of Sn compared with Pb. Herein, it is found that the synergistic effect of potassium thiocyanate (KSCN) in the Sn–Pb mixed perovskites can enlarge the grain size, enhance the crystallization, improve the film morphology, and obtain high‐quality perovskite films which effectively eliminate the bulk defects and smooth carrier transportation of Sn–Pb mixed perovskite solar cells. Through optimizing the concentration of KSCN, a high‐performance MA0.5FA0.5Pb0.5Sn0.5I3 solar cell with an efficiency of 15.14% and improved stability is obtained. This work lays a key foundation for the fabrication of efficient and stable Sn‐based or Sn–Pb mixed perovskite solar devices.

We estimate the size of US consumer gains from Chinese imports during 2004-2015. Using barcode-level price and expenditure data, we construct inflation rates under CES preferences, and use Chinese exports to Europe as an instrument. We find significant negative effects of Chinese imports on US prices. This effect is driven by both changes in the prices of existing goods and the entry of new goods and it is similar across consumer groups by income or region. A simple benchmarking exercise suggests that Chinese imports led to a 0.19 ppt annual reduction in the price index for consumer tradables. * We are grateful to Swati Dhingra,

The as-cast microstructure, mechanical properties and casting fluidity of ZA84 alloy containing TiC were investigated. The experimental results indicate that adding 0.5wt%TiC to ZA84 alloy can refine the as-cast microstructure, and do not cause the formation of any new phase. After 0.5wt%TiC was added to the ZA84 alloy, the morphology of ternary phases on the grain boundaries changed from coarse quasi-continuous net to fine disconnected net, and the distribution of ternary phases became dispersive and homogeneous. At the same time, the tensile properties of ZA84+0.5TiC alloy at room temperature were comparable to those of AZ91D alloy, and were higher than those of ZA84 alloy. At 150 ℃, the tensile and creep properties of ZA84＋0.5TiC alloy were also higher than those of ZA84 and AZ91D alloys. In addition, compared with the AZ91D alloy, the casting fluidity of ZA84＋0.5TiC alloy was slightly poor, but better than that of ZA84 alloy. The reason could be related to the effect of TiC on the solidification temperature range of ZA84 alloy.

Low dimensional (quasi-2D) and mixed dimensional (2D/3D) halide perovskites have emerged in the field of perovskite solar cells. They are more stable than their 3D homolog. However, most of the...

UPF and numerous others for useful suggestions. All errors remain our own. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

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