Monolayer transition metal dichalcogenides (TMDs) have become essential two-dimensional materials for their perspectives in engineering next-generation electronics. For related applications, the controlled growth of large-area uniform monolayer TMDs is crucial, while it remains challenging. Herein, we report the direct synthesis of 6-inch uniform monolayer molybdenum disulfide on the solid soda-lime glass, through a designed face-to-face metal-precursor supply route in a facile chemical vapor deposition process. We find that the highly uniform monolayer film, with the composite domains possessing an edge length larger than 400 µm, can be achieved within a quite short time of 8 min. This highly efficient growth is proven to be facilitated by sodium catalysts that are homogenously distributed in glass, according to our experimental facts and density functional theory calculations. This work provides insights into the batch production of highly uniform TMD films on the functional glass substrate with the advantages of low cost, easily transferrable, and compatible with direct applications.

Organic–inorganic hybrid perovskites are promising candidates for the next-generation solar cells. Many efforts have been made to study their structures in the search for a better mechanistic understanding to guide the materials optimization. Here, we investigate the structure instability of the single-crystalline CH3NH3PbI3 (MAPbI3) film by using transmission electron microscopy. We find that MAPbI3 is very sensitive to the electron beam illumination and rapidly decomposes into the hexagonal PbI2. We propose a decomposition pathway, initiated with the loss of iodine ions, resulting in eventual collapse of perovskite structure and its decomposition into PbI2. These findings impose important question on the interpretation of experimental data based on electron diffraction and highlight the need to circumvent material decomposition in future electron microscopy studies. The structural evolution during decomposition process also sheds light on the structure instability of organic–inorganic hybrid perovskites in solar cell applications.

No abstract

Objectives: To examine the relationship between loneliness and cognitive function and to explore the mediating role of physical health on the loneliness-cognition relationship in Chinese older adults (OAs). Method: Data came from a nationally representative sample of 14,199 Chinese OAs (aged 65+) from 2002, 2005, 2008, and 2011 waves of the Chinese Longitudinal Healthy Longevity Survey. A latent variable cross-lagged panel model combined with mediation analysis was used to determine the relationship between loneliness and cognitive function and the mediating effect of increase in the number of chronic conditions (ΔNCCs) on the ascertained loneliness-cognition relationship. Results: Severe loneliness at prior assessment points was significantly associated with poorer cognitive function at subsequent assessments, and vice versa. The ΔNCCs partially mediated this prospective reciprocal relationships, accounting for 2.58% of the total effect of loneliness on cognition and 4.44% of the total effect of cognition on loneliness, respectively. Discussion: Loneliness may predict subsequent cognitive decline, and vice versa. This loneliness-cognition relationship is partially explained by their impact on physical health. Multidisciplinary interventions aimed at reducing loneliness and cognitive decline per se and their associated risk factors as well as improving chronic illness management would be beneficial for emotional well-being and cognitive health in OAs.