As an interesting layered material, molybdenum disulfi de (MoS 2 ) has been extensively studied in recent years due to its exciting properties. However, the applications of MoS 2 in optoelectronic devices are impeded by the lack of high-quality p-n junction, low light absorption for mono-/multilayers, and the diffi culty for large-scale monolayer growth. Here, it is demonstrated that MoS 2 fi lms with vertically standing layered structure can be deposited on silicon substrate with a scalable sputtering method, forming the heterojunctiontype photodetectors. Molecular layers of the MoS 2 fi lms are perpendicular to the substrate, offering high-speed paths for the separation and transportation of photo-generated carriers. Owing to the strong light absorption of the relatively thick MoS 2 fi lm and the unique vertically standing layered structure,

Following the traditional naming of "eruptive flare" and "confined flares" but not implying a causal relationship between flare and coronal mass ejection (CME), we refer to the two kinds of large energetic phenomena occurring in the solar atmosphere as eruptive event and confined event, respectively: the former type refers to flares with associated CMEs, while the later type refers to flares without associated CMEs. We find that about 90% of X-class flares, the highest class in flare intensity size, are eruptive, but the rest 10% confined. To probe the question why the largest energy release in the solar corona could be either eruptive or confined, we have made a comparative study by carefully investigating 4 X-class events in each of the two types with a focus on the differences in their magnetic properties. Both sets of events are selected to have very similar intensity (X1.0 to X3.6) and duration (rise time less than 13 minutes and decaying time less than 9 minutes) in soft X-ray observations, in order to reduce the bias of flare size on CME occurrence. We find no difference in the total magnetic flux of the photospheric source regions for the two sets of events. However, we find that the occurrence of eruption (or confinement) is sensitive to the displacement of the location of the energy release, which is defined as the distance between the flare site and the flux-weighted magnetic center of the source active region. The displacement is 6 to 17 Mm for confined events, but is as large as 22 to 37 Mm for eruptive events, compared to the typical size of about 70 Mm for active regions studied. In other words, confined events occur closer to the magnetic center while the eruptive events tend to occur closer to the edge of active regions. Further, we have used potential-field source-surface model (PFSS) to infer the 3-D coronal magnetic field above source active regions. For each event, we calculate the coronal flux ratio of low corona (< 1.1 R ⊙ ) to high corona (≥ 1.1 R ⊙ ).We find that the confined events have a lower coronal flux ratio (< 5.7), while the eruptive events have a higher flux ratio(> 7.1). These results imply that a stronger overlying arcade field may prevent energy release in the low corona from being eruptive, resulting in flares without CMEs. A CME is more likely to occur if the overlying arcade field is weaker.

A MoSe2/Si heterojunction photodetector is constructed by depositing MoSe2 film with vertically standing layered structure on Si substrate. Graphene transparent electrode is utilized to further enhance the separation and transport of photogenerated carriers. The device shows excellent performance in terms of wide response spectrum of UV–visible–NIR, high detectivity of 7.13 × 1010 Jones, and ultrafast response speed of ≈270 ns, unveiling the great potential for the heterojunction for high‐performance optoelectronic devices.

It is generally accepted that the hydrophilic property of graphene can be affected by the underlying substrate. However, the role of intrinsic vs substrate contributions and the related mechanisms are vividly debated. Here, we show that the intrinsic hydrophilicity of graphene can be intimately connected to the position of its Fermi level, which affects the interaction between graphene and water molecules. The underlying substrate, or dopants, can tune hydrophilicity by modulating the Fermi level of graphene. By shifting the Fermi level of graphene away from its Dirac point, via either chemical or electrical voltage doping, we show enhanced hydrophilicity with experiments and first principle simulations. Increased vapor condensation on graphene, induced by a simple shifting of its Fermi level, exemplifies applications in the area of interfacial transport phenomena.