Lateral Flow through a Parallel Gap Driven by Surface Hydrophilicity and Liquid Edge Pinning for Creating Microlens Array

This letter proposes a surface-energy driven process for economically creating polymer microlens array (MLA) with well controllable curvatures. When a UV-curable prepolymer flows into a cell constructed by multiple holes on a top template and a flat substrate, since the edge pinning of the contact line, an array of curved air/prepolymer interface forms around each microhole of the template. Then a UV-radiation of the bulk prepolymer leads to a solid microlens array. The curvature of the air/prepolymer interface can be controlled by choosing materials with different interface free energy or varying the gap height mechanically

Enhanced Electrical and Optoelectronic Characteristics of Few-Layer Type-II SnSe/MoS₂ van der Waals Heterojunctions

van der Waals heterojunctions formed by stacking various two-dimensional (2D) materials have a series of attractive physical properties, thus offering an ideal platform for versatile electronic and optoelectronic applications. Here, we report few-layer SnSe/MoS₂ van der Waals heterojunctions and study their electrical and optoelectronic characteristics. The new heterojunctions present excellent electrical transport characteristics with a distinct rectification effect and a high current on/off ratio (∼1 × 10⁵). Such type-II heterostructures also generate a self-powered photocurrent with a fast response time (<10 ms) and exhibit high photoresponsivity of 100 A W^–1, together with high external quantum efficiency of 23.3 × 10³% under illumination by 532 nm light. Photoswitching characteristics of the heterojunctions can be modulated by bias voltage, light wavelength, and power density. The designed novel type-II van der Waals heterojunctions are formed from a combination of a transition-metal dichalcogenide and a group IV–VI layered 2D material, thereby expanding the library of ultrathin flexible 2D semiconducting devices

Strain and Interference Synergistically Modulated Optical and Electrical Properties in ReS₂/Graphene Heterojunction Bubbles

Two-dimensional (2D) material bubbles, as a straightforward method to induce strain, represent a potentially powerful platform for the modulation of different properties of 2D materials and the exploration of their strain-related applications. Here, we prepare ReS2/graphene heterojunction bubbles (ReS2/gr heterobubbles) and investigate their strain and interference synergistically modulated optical and electrical properties. We perform Raman and photoluminescence (PL) spectra to verify the continuously varying strain and the microcavity induced optical interference in ReS2/gr heterobubbles. Kelvin probe force microscopy (KPFM) is carried out to explore the photogenerated carrier transfer behavior in both strained ReS2/gr heterobubbles and ReS2/gr interfaces, as well as the oscillation of surface potential caused by optical interference under illumination conditions. Moreover, the switching of in-plane crystal orientation and the modulation of optical anisotropy of ReS2/gr heterobubbles are observed by azimuth-dependent reflectance difference microscopy (ADRDM), which can be attributed to the action of both strain effect and interference. Our study proves that the optical and electrical properties can be effectively modulated by the synergistical effect of strain and interference in a 2D material bubble

In-Plane Optical Anisotropy and Linear Dichroism in Low-Symmetry Layered TlSe

In-plane anisotropy of layered materials adds another dimension to their applications, opening up avenues in diverse angle-resolved devices. However, to fulfill a strong inherent in-plane anisotropy in layered materials still poses a significant challenge, as it often requires a low-symmetry nature of layered materials. Here, we report the fabrication of a member of layered semiconducting A^IIIB^VI compounds, TlSe, that possesses a low-symmetry tetragonal structure and investigate its anisotropic light–matter interactions. We first identify the in-plane Raman intensity anisotropy of thin-layer TlSe, offering unambiguous evidence that the anisotropy is sensitive to crystalline orientation. Further <i>in-situ</i> azimuth-dependent reflectance difference microscopy enables the direct evaluation of in-plane optical anisotropy of layered TlSe, and we demonstrate that the TlSe shows a linear dichroism under polarized absorption spectra arising from an in-plane anisotropic optical property. As a direct result of the linear dichroism, we successfully fabricate TlSe devices for polarization-sensitive photodetection. The discovery of layered TlSe with a strong in-plane anisotropy not only facilitates its applications in linear dichroic photodetection but opens up more possibilities for other functional device applications