Atomically thin heterostructures of transition-metal dichalcogenides (TMDs) with various geometrical and energy band alignments are the key materials for next generation flexible nano-electronics. The individual TMD monolayers can be adjoined laterally to construct in-plane heterostructures which are difficult to reach with the laborious pick up-and-transfer method of the exfoliated flakes. The ability to produce copious amounts of high quality layered heterostructures on diverse surfaces is highly desirable but it has remained a challenging issue. Here, we have achieved a direct synthesis of lateral heterostructures of monolayer TMDs: MoS 2 -WS 2 and MoSe 2 -WSe 2 . The synthesis was performed using ambient-pressure CVD with aromatic molecules as seeding promoters. We discuss possible growth behaviors, and we examine the symmetry and the interface of these heterostructures using second-harmonic generation and atomic-resolution scanning TEM. We found that the 1D interface of the lateral heterostructures picks the zigzag direction of the lattice instead of the armchair direction. Our method offers a controllable synthesis to obtain high-quality in-plane heterostructures of TMD atomic layers with one-dimensional interface geometry. MAIN TEXT:The heterostructure of materials with various geometrical and energy band alignments can exhibit electronic properties macroscopically different from their constituent materials 1-13 . They offer novel phenomena in semiconducting multiple quantum wells, such as interlayer Coulomb drag between charge carriers and phonons, exciton Bose condensation, emergent massive Dirac fermions and fractal quantum Hall, and diverse applications including the quantum cascade laser and the high-mobility 2D electron gas 1,7-10 . More recently, the ability to construct atomically thin heterostructures has allowed for the first realization of the Hofstadter butterfly in vertically-stacked graphene/h-BN heterostructures 7-9 and interlayer excitons in TMD heterojunctions [15][16][17][18] . These monolayer materials are the building blocks for constructing various heterostructures with atomically sharp interfaces in the absence of dangling bonds 3,19-28 . Moreover, the heterostructures can be functionalized by energy band alignments, and also by electrostatic gating to control the charge doping concentration 26,[29][30] . In particular, the diverse properties of individual TMDs monolayer (such as MoS 2 , MoSe 2 , WS 2 and WSe 2 ) provide promising candidates to further construction of various heterostructures for nano-science, and next generation optoelectronic and valleytronic devices 4,22, 31-37 .The band structures and diverse performances of these heterostructures are significantly determined by their crystalline phases and symmetry, and interface quality 38,39 . Second harmonic generation (SHG) was considered as a robust characterization tool on interfaces, symmetry, and twisting angles of the atomic layers in the heterostructures 39-47 . The analytic spherical aberration corrected scanning trans...

This study examines the role of cognitive and affective destination-image components in the formation of destination preferences from a multialternative/multiattribute perspective. In addition, the study examines the stability of those roles across three types of destinations. A total of 1,020 Taichung residents in Taiwan were administered an on-site questionnaire. The results indicated that cognitive and affective components of overall destination image influence tourists' destination preferences and that cognitive image impacts affective image. However, the importance of the two image components varied across natural, developed, and theme-park destinations. In addition, the findings confirmed that while some image attributes are universally important, other attributes are only important for specific types of destinations. Implications for theory, practice, and future research are provided.

Colloidal quantum dots which can emit red, green, and blue colors are incorporated with a micro-LED array to demonstrate a feasible choice for future display technology. The pitch of the micro-LED array is 40 μm, which is sufficient for high-resolution screen applications. The method that was used to spray the quantum dots in such tight space is called Aerosol Jet technology which uses atomizer and gas flow control to obtain uniform and controlled narrow spots. The ultra-violet LEDs are used in the array to excite the red, green and blue quantum dots on the top surface. To increase the utilization of the UV photons, a layer of distributed Bragg reflector was laid down on the device to reflect most of the leaked UV photons back to the quantum dot layers. With this mechanism, the enhanced luminous flux is 194% (blue), 173% (green) and 183% (red) more than that of the samples without the reflector. The luminous efficacy of radiation (LER) was measured under various currents and a value of 165 lm/Watt was recorded.

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There have been numerous efforts to increase the efficiency of solid-state lighting, lightemitting diodes (LEDs) and displays during the last decades. [1][2][3] As the technologies for fabricating GaN-based LEDs and for synthesizing semiconductor colloidal nanocrystals (NQDs) mature, hybrid NQD-GaN LEDs are becoming promising candidates for highly efficient multi-color lighting. The high quantum yield and photostability of colloidal NQDs offer the possibility for flexible, low cost, large area, and simply-processed optoelectronic devices, while their emission color can be tuned from the visible to the near infrared range by either changing their size or chemical composition. [4] Also the epitaxial growth of GaN has now reached the stage where GaN-based LEDs have an internal quantum efficiency of 80%. [5] Although their external quantum efficiency is inevitably limited by total internal reflection due to the high refractive index contrast with air, several approaches to improve the outcoupling efficiency have been realised implementing smart photonic crystal and waveguide designs. [6,7] Color conversion LEDs consisting of colloidal NQD emitters pumped by GaNbased LEDs overcome the drawback of NQDs, i.e. low carrier transfer. [8] A thin NQD layer deposited on LED surface absorbs the high energy photons that are electrically generated in the LED and subsequently reemits lower energy photons. As a result, there is no charge transfer among colloidal NQDs involved in this color conversion process. However, the efficiency of radiative energy transfer is relatively low, <10%, due to several energy loss steps in the transfer process, i.e. waveguided leaky mode losses, light scattering from the NQDs and

Polarizers play a key role in generating polarized light for display, imaging, and data communication, but adoption often suffers from high optical loss. Recently, due to superior optoelectronic properties, halide perovskites have been widely developed for lighting applications; however, highly polarized emission (polarization degree >0.8) has not yet been realized with perovskites. Herein, by incorporating inkjet printing and an anodic aluminum oxide (AAO) confinement strategy, highly ordered perovskite nanowire (NW) arrays are demonstrated for anisotropic optical applications. The optical device based on perovskite NW arrays reveals a high photoluminescence external quantum efficiency of 21.6% and emits highly polarized light with polarization degree up to 0.84. The highly polarized emission from perovskite NW arrays has potential to considerably reduce the optical loss of polarizers, which may attract great interest in developing polarized light sources for next‐generation optoelectronic applications.

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Researchers have recently revealed that hybrid lead halide perovskites exhibit ferroelectricity, which is often associated with other physical characteristics, such as a large nonlinear optical response. In this work, the nonlinear optical properties of single crystal inorganic-organic hybrid perovskite CH 3 NH 3 PbBr 3 are studied. By exciting the material with a 1044 nm laser, strong two-photon absorption-induced photoluminescence in the green spectral region is observed. Using the transmission open-aperture Z-scan technique, the values of the two-photon absorption coefficient are observed to be 8.5 cm GW −1 , which is much higher than that of standard two-photon absorbing materials that are industrially used in nonlinear optical applications, such as lithium niobate (LiNbO 3 ), LiTaO 3 , KTiOPO 4 , and KH 2 PO 4 . Such a strong two-photon absorption effect in CH 3 NH 3 PbBr 3 can be used to modulate the spectral and spatial profiles of laser pulses, as well as to reduce noise, and can be used to strongly control the intensity of incident light. In this study, the superior optical limiting, pulse reshaping, and stabilization properties of CH 3 NH 3 PbBr 3 are demonstrated, opening new applications for perovskites in nonlinear optics.