Periodic Arrangement Research Articles

Microstructure evolution of CdZnTe crystals irradiated by heavy ions

Consideration of irradiation effects is important for in-orbit operation and radiation protection in aerospace applications. The configuration of irradiation defects and their impact on deteriorating the carrier transport properties of CZT crystals need to be clarified. In this study, the microdefect evolution mechanism of CdZnTe (CZT) crystals under 10 MeV Chlorine (Cl) ion irradiation at flux of 1×1010∼1×1012 n·cm-2 are investigated. The stacking faults first appear in the CZT crystal at 4.5×10-4 displacement per atom (dpa), which are categorized into slip-type, gap-type and vacancy-type. In order to hinder the further expansion of stacking fault, S-shaped stacking fault dipole appears. When the dpa reaches 4.5×10-2, the local phase transition occurs in the damage zone to form CuPt-A ordered phase with ZnTe/CdTe periodic arrangement because the fluctuation in local composition and strain caused by cascade collisions. The deterioration of electric field distribution and charge collection caused by irradiation damage layer leads to the decrease of γ-ray detection ability. The energy resolution (ER) of the CZT detector for γ-ray can be maintained at 30.6% when the ion flux accumulates to 1×1012 n·cm-2, revealing high irradiation hardness. Consequently, these findings provide a theoretical basis for the radiation damage recovery of CZT detectors, further demonstrating that CZT crystals are the most competitive new generation of room-temperature nuclear radiation detection materials, and can provide radiation protection strategies for similar compound semiconductor materials.

Noise filter using a periodic system of dual Helmholtz resonators

This study investigates noise reduction using a periodic arrangement of dual Helmholtz resonators and explores the introduction of defects within this periodic structure. The transfer matrix method was employed to carry out theoretical research. The computations of the interface response function approach results are verified, and consistent outcomes are demonstrated. The simulation results highlight the distinctive dual resonance frequencies of dual Helmholtz resonators. By differentiating dual Helmholtz resonators from traditional Helmholtz resonators, prospective applications for low-frequency noise reduction are envisioned. In this contribution, introducing defects in the middle of perfect dual Helmholtz resonators adds more value to the acoustic filter. In particular, the first neck and cavity of the defective dual Helmholtz resonator. This study shows that introducing a 2D-defect into identical dual Helmholtz resonators can improve the transmission of defect modes by taking advantage of the advantageous interaction of the resonant modes. In such arrangements, the entire structure functioned as a potent selective filter.

Widening the frequency bandgap and reducing thermal conductivity in phononic crystals by tuning structural parameters using a novel computational simulation method

AbstractThis paper introduces and models a phononic structure based on single-crystal silicon, aiming to investigate the width of its frequency bandgap and the impact of key parameters on thermal conductivity. The modeled phononic crystal structure features a periodic arrangement of cylindrical holes in a silicon matrix. This research holds the potential to enhance thermal management performance of thermal metamaterials. Utilizing a 3D finite element method (FEM) model in COMSOL, we have computed phonon dispersion to estimate thermal conductivity. The study systematically has explored the influence of phononic crystal parameters—specifically, porosity, lattice constant, and thickness—along with their interactions on both thermal conductivity and frequency bandgap width.A comprehensive investigation of these parameters has been conducted for their optimization to achieve the maximum frequency bandgap width and minimum thermal conductivity using the response surface method model. Eigenfrequencies and wave vector parameters are extracted from the finite element model using a MATLAB script. Subsequently, thermal conductivity is calculated through the Callaway–Holland model, a simplification of the Boltzmann transport equation (BTE).Our results indicate that the frequency bandgap begins to form at approximately 43% porosity for a lattice constant and thickness of 100 nm each. Furthermore, adjusting the parameters led to a significant reduction in thermal conductivity, decreasing from 43.89 W m−1 K−1 to 0.39 W m−1 K−1. The novelty of our research lies in thermal conductivity control of phononic crystal metamaterials through their parameter variations, or a predictive method of thermal conductivity and its parameter sensitivity. This study advances the state of the art in phononic crystal metamaterial research, contributing to improved thermal management performance by enlarging frequency bandgaps.Overall, our findings deepen the understanding of how porosity, lattice constant, and thickness influence thermal conductivity and frequency bandgap width. They offer valuable insights into optimizing phononic crystal parameters, enhancing thermal management performance, and designing more efficient and effective phononic crystal structures.

Anthracnose Caused by Colletotrichum spaethianum on Polygonatum odoratum var. pluriflorum in Korea.

Polygonatum odoratum var. pluriflorum (Miq.) Ohwi (Asparagaceae), commonly known as Lesser Solomon's seal, is a perennial herbaceous plant widely distributed in the temperate regions of the Northern Hemisphere. It is known for tea and contains various pharmacologically active compounds (Chang et al. 2007). In September 2021, previously unseen anthracnose was encountered on Polygonatum odoratum var. pluriflorum in Chuncheon (37°45'07''N; 127°47'45''E) and Wanju (35°38'47''N; 127°31'16''E), Korea, with a disease incidence of 20 to 30% of the inspected plants. The disease symptoms begin with leaf yellowing (chlorosis) along the margins, progressing toward the central part of the leaf. As the disease progressed, brown necrotic lesions developed, covered with small, dark dots, indicating the presence of conidiomata of Colletotrichum. The disease often led to leaf blight, resulting in concentric lesions of a periodic and concentric arrangement of conidiomata, forming circular patterns within the affected tissue. It expanded rapidly during the rainy season producing water-soaked lesions but nearly slowed down during the dry season, leaving the plant with a ragged appearance. Monoconidial isolates were obtained from five fresh samples collected in Wanju, of which a representative isolate was deposited in the Korean Agricultural Culture Collection (KACC410442), and the dried specimen was housed at the herbarium of Jeonbuk National University (JBNU0135). Morphological characteristics of the fungus were examined with fresh and naturally infected leaves. Setae (n = 30) were dark brown to nearly blackish, 45 to 172 um long, 4.1 to 6.1 µm wide at the base, and becoming narrower upwards, apex pointed, 2 to 4-septate. Conidia were 1-celled, sometimes uniseptate before germination, slightly curved, with an acute or rounded apex and a more or less truncate base, and 11.4 to 23.2 × 3.1 to 4.2 µm. Appressoria were single or in groups, dark brown, lobate, irregularly shaped, and 6.0 to 11.9 × 7.0 to 14.8 µm. Two-week-old colonies grown on PDA at 25 ℃ reached 30-35 mm in diam., initially white, turning gray with age, with cottony aerial mycelia. These morphological characteristics were in good agreement with those of C. spaethianum (Damm et al. 2009; Liu et al. 2020). To confirm the morphology-based determination, genomic DNA was extracted from KACC410442, and multi-loci sequences of the internal transcribed spacer region (ITS) rDNA, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), actin (actA), chitin synthase (CHS1), histone (HIS3) and tubulin (TUB2) genes were determined, as outlined by Cannon et al. (2012) and Damm et al. (2009). The resulting sequences obtained in this study were registered to GenBank (PP739190 for ITS, PP741985 for GAPDH, PP741986 for actA, PP741987 for CHS1, PP741988 for HIS3, and PP741989 for TUB2) and compared with other sequences on GenBank using the BLASTn search tool. The results showed 100% identity to other C. spaethianum sequences (e.g., MT611068 for ITS, MN400659 for actA, OP965007 for CHS1, OR060963 for GAPDH, PP480643 for HIS3, and OQ613727 for TUB2). In a maximum parsimony tree, the Korean isolate formed a well-supported clade (100% bootstrap value) with reference sequences of C. spaethianum. Pathogenicity was tested by spraying a conidial suspension (1×104 conidia/ml) from a two-week-old culture onto ten leaves of three potted plants, without wounding. Ten water-sprayed leaves were served as controls. The plants were maintained in a dew chamber and later moved to a greenhouse at 25 to 30 °C. After two weeks, all inoculated plants developed anthracnose symptoms, while the control plants remained symptomless. The fungus isolated from the inoculated plants was morphologically identical to that initially observed, fulfilling Koch's postulates. C. spaethianum has been known on various plant species, but mostly on the Asparagaceae, including Anemarrhena (Okorley et al. 2019), Hosta (Damm et al. 2009; Cheon and Jeon 2016), and Polygonatum (Liu et al. 2020; Ma et al. 2021). To our knowledge, this is the first report of anthracnose caused by C. spaethianum on P. odoratum var. pluriflorum in Korea, highlighting the continuous need for disease management and control in the cultivation of this plant.

Light-Induced Polaronic Crystals in Single-Layer Transition Metal Dichalcogenides.

Light-induced ordered states can emerge in materials after irradiation with ultrafast laser pulses. However, their prediction is challenging because the inverted band occupation confounds our chemical intuition. Hence, we use a recently developed constrained density functional perturbation theory approach to systematically screen single-layer transition metal dichalcogenides (TMDs) for light-induced ordered states. We demonstrate that all examined single-layer TMDs reveal similar light-induced charge orderings. The corresponding reconstructions are periodic arrangements of polarons (polaronic crystals), characterized by triangular metal clusters and having no equivalent at equilibrium conditions. The polarons are accompanied by localized midgap states in the electronic band structure, detectable by experimental methods. We assess the selenides as the most promising candidates for potential photoexcitation experiments because they transition at low critical fluences, have low transition barriers, and maintain an open band gap under photoexcitation. Our work paves the way for innovative material design approaches targeting light-induced phases.

Influence of randomly placed resonant aggregates on the attenuation properties of metaconcrete: A numerical study

Concrete is a key material for many structural components in engineering, but its acoustic performance remains under discussion. Hence, the potential of the so-called metaconcrete has gained attention in research, mainly due to its capability to control vibrations and sound transmission when resonant aggregates are embedded in the concrete. These resonant aggregates are designed to have resonant frequencies regarding frequency bands of interest, so the interaction with the incident sound waves is attenuated within those frequencies. While available research has focused on the characterization of metaconcrete with a periodic arrangement of resonant aggregates, there is a gap regarding how their random allocation affects the characterization of metaconcrete. This study focuses on the numerical analysis of metaconcrete and the influence of randomly placed resonant aggregates on its attenuation properties. The numerical approach concentrates on the aggregate's material composition, location and volume fraction within the concrete to identify configurations that exhibit great wave attenuation. The results have shown that the attenuation effect is substantially advantageous when using a multi-frequency configuration for aggregates within the metaconcrete. Additionally, the random embedding of resonant aggregates offers a practical solution for their application in concrete structures.

Research on Magnetic Field of Permanent Magnet Rolls Arranged Periodically in Circumferential—Axial Direction

The separation of non-magnetic non-ferrous metals such as copper and aluminum from scrapped automobiles is a critical area of research due to the increasing number of end-of-life vehicles. Traditional eddy current separation methods have limitations, particularly in handling large-sized broken copper and aluminum parts. This paper proposes a novel magnetic roller model featuring a circumferential–axial periodic arrangement of permanent magnets. This study explores the external magnetic field distribution of this new roller design by constructing an equivalent current model, solving magnetic scalar potential equations, and employing simulation tools. The findings indicate that the new magnet array enhances both the magnetic field strength and the range of the external magnetic field, leading to improved separation efficiency of large-sized metal fragments. The results provide a theoretical basis for advancing the separation technology of large-sized broken copper and aluminum parts in scrapped automobiles, offering potential improvements in the recycling of non-ferrous metals from end-of-life vehicles.

A sub-wavelength metamaterial layer for reducing underwater noise radiation of marine structures

Reducing the underwater noise radiated by marine structures is a critical issue for improving submarine stealth or limiting the anthropogenic impact of commercial ships. In this study, we propose a lightweight passive solution based on a metamaterial to efficiently reduce the noise at low frequency (< 1000 Hz) that can be transmitted through the shell plating of a marine vessel. This solution is made of a soft acoustically impervious poro-elastic foam in which inclusions are periodically positioned. Added to a plate, this metamaterial outperforms the mass law in the sub-wavelength domain when separating two air domains. This performance is due to the periodic arrangement of inclusions in the foam, creating a vibro-acoustic bandgap. The aim of this study is therefore to assess this solution where the domain of the transmitted acoustic wave is water. Firstly, numerical results on an unbounded plate are validated alongside the theoretical model of a flexible partition. When the metamaterial layer is added to the plate, it is shown that a vibro-acoustic bandgap still exists in the transmitted wavenumber domain, and that this solution is a good candidate for achieving the objectives. Experimental measurements on a finite structure are then conducted and compared to numerical results

Periodic Single-Metal Site Catalysts: Creating Homogeneous and Ordered Atomic-Precision Structures.

Heterogeneous single-metal-site catalysts (SMSCs), often referred to as single-atom catalysts (SACs), demonstrate promising catalytic activity, selectivity, and stability across a wide spectrum of reactions due to their rationally designed microenvironments encompassing coordination geometry, binding ligands, and electronic configurations. However, the inherent disorderliness of SMSCs at both atomic scale and nanoscale poses challenges in deciphering working principles and establishing the correlations between microenvironments and the catalytic performances of SMSCs. The rearrangement of randomly dispersed single metals into homogeneous and atomic-precisely structured periodic single-metal site catalysts (PSMSCs) not only simplifies the chaos in SMSCs systems but also unveils new opportunities for manipulating catalytic performance and gaining profound insights into reaction mechanisms. Moreover, the synergistic effects of adjacent single metals and the integration effects of periodic single-metal arrangement further broaden the industrial application scope of SMSCs. This perspective offers a comprehensive overview of recent advancements and outlines prospective avenues for research in the design and characterizations of PSMSCs, while also acknowledging the formidable challenges encountered and the promising prospects that lie ahead.

Band Structure Engineering in 2D Metal-Organic Frameworks.

The design of 2D metal-organic frameworks (2D MOFs) takes advantage of the combination of the diverse electronic properties of simple organic ligands with different transition metal (TM) centers. The strong directional nature of the coordinative bonds is the basis for the structural stability and the periodic arrangement of the TM cores in these architectures. Here, direct and clear evidence that 2D MOFs exhibit intriguing energy-dispersive electronic bands with a hybrid character and distinct magnetic properties in the metal cores, resulting from the interactions between the TM electronic levels and the organic ligand π-molecular orbitals, is reported. Importantly, a method to effectively tune both the electronic structure of 2D MOFs and the magnetic properties of the metal cores by exploiting the electronic structure of distinct TMs is presented. Consequently, the ionization potential characteristic of selected TMs, particularly the relative energy position and symmetry of the 3d states, can be used to strategically engineer bands within specific metal-organic frameworks. These findings not only provide a rationale for band structure engineering in 2D MOFs but also offer promising opportunities for advanced material design.

Transverse magneto-optical Kerr effect enhancement in si–ni nanogratings by mie and surface lattice resonances

We demonstrate experimentally that a one-dimensional array of silicon nanowires periodically placed on a nickel substrate enhances the transverse magneto-optical Kerr effect (TMOKE) compared to a nickel film. The enhancement mechanism is associated with the excitation of two types of resonances: multipole Mie resonances in each nanowire and surface lattice resonances (SLRs) emerging from the periodic arrangement of the nanowires. The maximal TMOKE values reached up to 1.9 % and 2.6 % due to the excitation of SLR and a magnetic dipole resonance, respectively. When the SLR is excited, the spectral width of the TMOKE enhancement is narrower compared to the case of the magnetic dipole resonance.

Porous cellulose photonic film via controlled unidirectional interlayer freezing for rapid visual sensing

Structure color, arising from the interaction of light with regularly arranged sub-micrometer-sized structures, has spurred interest in sensor design. However, typical cellulose nanocrystal (CNC) photonic films derived from biomass, known for their sustainability and cost-effectiveness, often suffer from limited sensitivity and slow response times due to their dense structure. To address this challenge, we have utilized a unidirectional interlayer freezing-photopolymerization strategy to introduce porous structures into CNC photonic films without compromising their vibrant structural color. This method harnesses ice crystal-induced lamellar pores while preserving the periodic arrangement of CNCs. The underlying mechanism of ice kinetics and CNC assembly is established, highlighting the transition from non-iridescent aerogels to iridescent, porous photonic films. The resulting porous CNC photonic film exhibits apparent color response and rapid sensing capabilities in response to various solvent stimuli, outperforming its non-porous counterparts. We have validated the film as a portable vapor detector for rapid visualized alcohol detection. This approach provides promising developments in sustainable, highly responsive sensor technologies.

Off-axis viewing angle control technology applied to displays

ABSTRACT With the development of display technology and the expansion of application fields, such as vehicle/airborne displays, medical imaging displays, industrial control displays, etc., spatial constraints of these displays often result in viewers observing them at specific off-axis viewing angles. Therefore, the frequently using demands of off-axis viewing angles lead to increasing requirements for the viewing angle performance of displays. A method to enhance the off-axis viewing angle effect is proposed in this paper by attaching a designed liquid crystal cell on the surface of the display to control the emission direction. When an appropriate driving voltage is applied to the liquid crystal cell, the liquid crystal molecules align in a specific periodic arrangement, creating an optical effect similar to micro/nano structured light control devices. Different driving voltages induce distinct modulations of light within the liquid crystal layer. When no driving voltage is applied, the frontal viewing angle effect of the display is optimal, suitable for vertical viewing by a single individual, as an on-axis viewing mode. When a driving voltage is applied, certain off-axis viewing angle properties such as brightness is increased and colour shift is reduced, making it suitable as an off-axis viewing mode. In practical use, individuals can freely switch between these two display modes based on their actual needs.

Lithiation Induced Hetero-Superlattice Zn/ZnLi as Stable Anode for Aqueous Zinc-Ion Batteries.

Three dimensional (3D) framework structure is one of the most effective ways to achieve uniform zinc deposition and thus inhibit the Zn dendrites growth in working Zn metallic anode. A major challenge facing for the most commonly used 3D zincophilic hosts is that the zincophilic layer tends to peel off during repeatedly cycling, making it less stable. Herein, for the first time, a hetero-superlattice Zn/ZnLi (HS-Zn/ZnLi) anode containing periodic arrangements of metallic Zn phase and zincophilic ZnLi phase at the nanoscale, is well designed and fabricated via electrochemical lithiation method. Based on binding energy and stripping energy calculation, and the operando optical observation of plating/stripping behaviors, the zincophilic ZnLi sites with a strong Zn adsorption ability in the interior of the 3D ZnLi framework structure can effectively guide uniform Zn nucleation and dendrite-free zinc deposition, which significantly improves the cycling stability of the HS-Zn/ZnLi alloy (over 2800 h without a short-circuit at 2 mA cm-2). More importantly, this strategy can be extended to HS-Zn/ZnNa and HS-Zn/ZnK anodes that are similar to the HS-Zn/ZnLi microstructure, also displaying significantly enhanced cycling performances in AZIBs. This study can provide a novel strategy to develop the dendrite-free metal anodes with stable cycling performance.

Lithiation Induced Hetero‐Superlattice Zn/ZnLi as Stable Anode for Aqueous Zinc‐Ion Batteries

AbstractThree dimensional (3D) framework structure is one of the most effective ways to achieve uniform zinc deposition and thus inhibit the Zn dendrites growth in working Zn metallic anode. A major challenge facing for the most commonly used 3D zincophilic hosts is that the zincophilic layer tends to peel off during repeatedly cycling, making it less stable. Herein, for the first time, a hetero‐superlattice Zn/ZnLi (HS−Zn/ZnLi) anode containing periodic arrangements of metallic Zn phase and zincophilic ZnLi phase at the nanoscale, is well designed and fabricated via electrochemical lithiation method. Based on binding energy and stripping energy calculation, and the operando optical observation of plating/stripping behaviors, the zincophilic ZnLi sites with a strong Zn adsorption ability in the interior of the 3D ZnLi framework structure can effectively guide uniform Zn nucleation and dendrite‐free zinc deposition, which significantly improves the cycling stability of the HS−Zn/ZnLi alloy (over 2800 h without a short‐circuit at 2 mA cm−2). More importantly, this strategy can be extended to HS−Zn/ZnNa and HS−Zn/ZnK anodes that are similar to the HS−Zn/ZnLi microstructure, also displaying significantly enhanced cycling performances in AZIBs. This study can provide a novel strategy to develop the dendrite‐free metal anodes with stable cycling performance.

Multiple parameters control of square superlattice plasma photonic crystal

We present a novel square superlattice plasma photonic crystal (PPC) fabricated by periodic arrangement of different-sized gas discharge tubes and Al2O3 dielectric rods. The effects of the plasma, the number and location of Al2O3 rods, and the angular orientation of PPCs on the microwave transmission characteristics have been demonstrated. For the simple square lattice, a PBGa in the range of 13.40–14.20 GHz is obtained. For the square superlattice, an additional PBGb in the range of 14.35–15.10 GHz develops. While PBGa and PBGb are primarily dependent on the square sublattices of plasma rods and Al2O3 rods, respectively, a synergistic effect arising from the interplay between these two sublattices is suggested. Moreover, a new PBGc is achieved by changing the rotation angle of the PPC to 45° The multiple parameters control of square superlattice PPC may inspire new strategies for designing fully bandgap-tunable PCs and may find potential applications in various fields.

A Comprehensive Study on Electrospun Cholesteric Liquid Crystal Core Fibers for Detecting Volatile Organic Compounds

Encapsulation of the cholesteric liquid crystal (CLC) into the core of poly(vinylpyrrolidone) (PVP) microfibers is accomplished via coaxial electrospinning technology and is applied to detect volatile organic compounds (VOCs). The impacts of various process parameters on the morphology of CLC fibers are deeply explored. The periodic arrangement of CLC molecules within the fibers enables the reflection of specific wavelengths. Consequently, changes in the reflected color of the CLC fiber membrane allow for the measurement and analysis of targeted gas molecules. The dynamic response of CLC fibers upon exposure to organic vapor is observed by a polarizing optical microscope, and its gray scale is used to quantitatively analyze the changes of reflected light signals of CLC fibers. Furthermore, the study investigates the reaction time for the failure of CLC molecular planar alignment in the CLC fiber membrane when subjected to perturbations induced by organic gases. The CLC fiber sensor exhibits heightened sensitivity to gases characterized by greater polarity. In light of potential future advancements, it is suggested that the spun fibers imbued with responsive properties through the incorporation of a liquid crystal core exhibit promise as a next-generation sensor technology in textile form, well-suited for applications in wearable technology.

Molecular Dynamics Simulation Study of Aluminum-Copper Alloys' Anisotropy under Different Loading Conditions and Different Crystal Orientations.

The commonly used aluminum-copper alloys in industry are mainly rolled plates and extruded or drawn bars. The aluminum-copper alloys' anisotropy generated in the manufacturing process is unfavorable for subsequent applications. Its underlying mechanism shall be interpreted from a microscopic perspective. This paper conducted the loading simulation on Al-4%Cu alloy crystals at the microscopic scale with molecular dynamics technology. Uniaxial tension and compression loading were carried out along three orientations: X-<1¯12>, Y-<11¯1>, and Z-<110>. It analyzes the micro-mechanisms that affect the performance changes of aluminum-copper alloys through the combination of stress-strain curves and different organizational analysis approaches. As shown by the results, the elastic modulus and yield strength are the highest under tension along the <11¯1> direction. Such is the case for the reasons below: The close-packed plane of atoms ensures large atomic binding forces. In addition, the Stair-rod dislocation forms a Lomer-Cottrell dislocation lock, which has a strengthening effect on the material. The elastic modulus and yield strength are the smallest under tension along the <110> direction, and the periodic arrangement of HCP atom stacking faults serves as the main deformation mechanism. This is because the atomic arrangement on the <110> plane is relatively loose, which tends to cause atomic misalignment. When compressed in different directions, the plastic deformation mechanism is mainly dominated by dislocations and stacking faults. When compressed along the <110> direction, it has a relatively high dislocation density and the maximum yield strength. That should be attributed to the facts below. As the atomic arrangement of the <110> plane itself was not dense originally, compression loading would cause an increasingly tighter arrangement. In such a case, the stress could only be released through dislocations. This research aims to provide a reference for optimizing the processing technology and preparation methods of aluminum-copper alloy materials.

Strong Cavity-Optomechanical Transduction of Nanopillar Motion.

Nanomechanical resonators can serve as ultrasensitive, miniaturized force probes. While vertical structures such as nanopillars are ideal for this purpose, transducing their motion is challenging. Pillar-based photonic crystals (PhCs) offer a potential solution by integrating optical transduction within the pillars. However, achieving high-quality PhCs is hindered by inefficient vertical light confinement. Here, we present a full-silicon photonic crystal cavity based on nanopillars as a platform for applications in force sensing and biosensing areas. Its unit cell consists of a silicon pillar with a larger diameter at its top portion than at the bottom, which allows vertical light confinement and an energy band gap in the near-infrared range for transverse-magnetic polarization. We experimentally demonstrate optical cavities with Q factors exceeding 103, constructed by inserting a defect within a periodic arrangement of this type of pillars. Each nanopillar naturally behaves as a nanomechanical cantilever, making the fabricated geometries excellent optomechanical (OM) photonic crystal cavities in which the mechanical motion of each nanopillar composing the cavity can be optically transduced. These geometries display enhanced mechanical properties, cost-effectiveness, integration possibilities, and scalability. They also present an alternative in front of the widely used suspended Si beam OM cavities made on silicon-on-insulator substrates.

Self-Cleaning Hydrophobic Coating Composed of Micro/Nano-Imprinted Polydimethylsiloxane with Enhanced Light In-Coupling Capabilities.

In this study, we have optimized optically transparent polydimethylsiloxane (PDMS) hydrophobic coating on glass substrates that exhibit self-cleaning as well as enhanced light in-coupling capabilities. Micro/nano textures on the surface of PDMS were introduced through micro/nanoimprinting to achieve light trapping as well as self-cleaning abilities. Comprehensive studies show that the periodic arrangement of the micro/nanopatterned features has enabled enhanced inward transmission of light in the visible range along with superior hydrophobicity. The water contact angle (WCA) measurements on these coatings demonstrated a superior capacity for self-cleaning with a WCA of about 117°. Subsequently, when these transparent and hydrophobic coatings were deposited on commercial silicon solar cells, they showed a 15.8% increment in efficiency due to enhanced light in-coupling with a nanopatterned PDMS coating.