Sodium Niobate Nanowires Embedded PVA-Hydrogel-Based Triboelectric Nanogenerator for Versatile Energy Harvesting and Self-Powered CO Gas Sensor.

The surging demand for sustainable energy solutions and adaptable electronic devices has led to the exploration of alternative and advanced power sources. Triboelectric Nanogenerators (TENGs) stand out as a promising technology for efficient energy harvesting, but research on fully flexible and environmental friendly TENGs still remain limited. In this study, an innovative approach is introduced utilizing an ionic-solution modified conductive hydrogel embedded with piezoelectric sodium niobate nanowires-based Triboelectric Nanogenerator (NW-TENG), offering intrinsic advantages to healthcare and wearable devices. The synthesized NW-TENG, with a 12.5 cm2 surface area, achieves peak output performance, producing ≈840 V of voltage and 2.3 µC of charge transfer, respectively. The rectified energy powers up 30 LEDs and a stopwatch; while the NW-TENG efficiently charges capacitors from 1µF to 100 µF, reaching 1 V within 4 to 65 s at 6 Hz. Integration with prototype carbon monoxide (CO) gas sensor transform the device into a self-powered gas sensory technology. This study provides a comprehensive understanding of nanowire effects on TENG performance, offering insights for designing highly flexible and environmentally friendly TENGs, and extending applications to portable self-powered gas sensors and wearable devices.

Surface Passivation by Sulfur-Based 2D (TEA)2PbI4 for Stable and Efficient Perovskite Solar Cells.

Perovskite solar cells (PSCs) with superior performance have been recognized as a potential candidate in photovoltaic technologies. However, defects in the active perovskite layer induce nonradiative recombination which restricts the performance and stability of PSCs. The construction of a thiophene-based 2D structure is one of the significant approaches for surface passivation of hybrid PSCs that may combine the benefits of the stability of 2D perovskite with the high performance of three-dimensional (3D) perovskite. Here, a sulfur-rich spacer cation 2-thiopheneethylamine iodide (TEAI) is synthesized as a passivation agent for the construction of a three-dimensional/two-dimensional (3D/2D) perovskite bilayer structure. TEAI-treated PSCs possess a much higher efficiency (20.06%) compared to the 3D perovskite (MA0.9FA0.1PbI3) devices (17.42%). Time-resolved photoluminescence and femtosecond transient absorption spectroscopy are employed to investigate the effect of surface passivation on the charge carrier dynamics of the 3D perovskite. Additionally, the stability test of TEAI-treated perovskite devices reveals significant improvement in humid (RH ∼ 46%) and thermal stability as the sulfur-based 2D (TEA)2PbI4 material self-assembles on the 3D surface, making the perovskite surface hydrophobic. Our findings provide a reliable approach to improve device stability and performance successively, paving the way for industrialization of PSCs.

Deep learning approach for inverse design of metasurfaces with a wider shape gamut.

While the large design degrees of freedom (DOFs) give metasurfaces a tremendous versatility, they make the inverse design challenging. Metasurface designers mostly rely on simple shapes and ordered placements, which restricts the achievable performance. We report a deep learning based inverse design flow that enables a fuller exploitation of the meta-atom shape. Using a polygonal shape encoding that covers a broad gamut of lithographically realizable resonators, we demonstrate the inverse design of color filters in an amorphous silicon material platform. The inverse-designed transmission-mode color filter metasurfaces are experimentally realized and exhibit enhancement in the color gamut.

Development of Nickel-Based Negative Tone Metal Oxide Cluster Resists for Sub-10 nm Electron Beam and Helium Ion Beam Lithography.

Hybrid metal-organic cluster resist materials, also termed as organo-inorganics, demonstrate their potential for use in next-generation lithography owing to their ability for patterning down to ∼10 nm or below. High-resolution resist patterning is integrally associated with the compatibility of the resist and irradiation of the exposure source. Helium ion beam lithography (HIBL) is an emerging approach for the realization of sub-10 nm patterns at considerably lower line edge/width roughness (LER/LWR) and higher sensitivity as compared to electron beam lithography (EBL). Here, for the first time, a negative tone resist incorporating nickel (Ni)-based metal-organic clusters (Ni-MOCs) was synthesized and patterned using HIBL and EBL at 30 keV. This resist comprises a nickel-based metal building unit covalently linked with the organic ligand: m-toluic acid (C8H8O2). Dynamic light scattering confirmed a narrow size distribution of ∼2 nm for metal-organic cluster (MOC) formulations. High-resolution ∼9 nm HIBL line patterns were well developed at a sensitivity of 22 µC/cm2 and at a significantly low LER and LWR of 1.81 ± 0.06 and 2.90 ± 0.06 nm, respectively. Analogous high-resolution patterns were also observed in EBL with a sensitivity of 473 µC/cm2. Hence, the Ni-MOC-based resist investigated using HIBL and EBL elucidates the ability of its potential for the sub-10 nm technology node, under standard processing conditions.

Polyarylenesulfonium Salt as a Novel and Versatile Nonchemically Amplified Negative Tone Photoresist for High-Resolution Extreme Ultraviolet Lithography Applications.

The present report demonstrates the potential of a polyarylenesulfonium polymer, poly[methyl(4-(phenylthio)-phenyl)sulfoniumtrifluoromethanesulfonate] (PAS), as a versatile nonchemically amplified negative tone photoresist for next-generation lithography (NGL) applications starting from i-line (λ ∼ 365 nm) to extreme ultraviolet (EUV, λ ∼ 13.5 nm) lithography. PAS exhibited considerable contrast (γ), 0.08, toward EUV and patterned 20 nm features successfully.

Patterning highly ordered arrays of complex nanofeatures through EUV directed polarity switching of non chemically amplified photoresist.

Given the importance of complex nanofeatures in the filed of micro-/nanoelectronics particularly in the area of high-density magnetic recording, photonic crystals, information storage, micro-lens arrays, tissue engineering and catalysis, the present work demonstrates the development of new methodology for patterning complex nanofeatures using a recently developed non-chemically amplified photoresist (n-CARs) poly(4-(methacryloyloxy)phenyl)dimethylsulfoniumtriflate) (polyMAPDST) with the help of extreme ultraviolet lithography (EUVL) as patterning tool. The photosensitivity of polyMAPDST is mainly due to the presence of radiation sensitive trifluoromethanesulfonate unit (triflate group) which undergoes photodegradation upon exposure with EUV photons, and thus brings in polarity change in the polymer structure. Integration of such radiation sensitive unit into polymer network avoids the need of chemical amplification which is otherwise needed for polarity switching in the case of chemically amplified photoresists (CARs). Indeed, we successfully patterned highly ordered wide-raging dense nanofeatures that include nanodots, nanowaves, nanoboats, star-elbow etc. All these developed nanopatterns have been well characterized by FESEM and AFM techniques. Finally, the potential of polyMAPDST has been established by successful transfer of patterns into silicon substrate through adaptation of compatible etch recipes.

New polyoxometalates containing hybrid polymers and their potential for nano-patterning.

Two new polyoxometalate (POM)-based hybrid monomers (Bu4 N)5 (H)[P2 V3 W15 O59 {(OCH2 )3 CNHCO(CH3 )CCH2 }] (2) and (S(CH3 )2 C6 H4 OCOC(CH3 )=CH2 )6 [PV 2Mo10 O40 ] (5) were developed by grafting polymerizable organic units covalently or electrostatically onto Wells-Dawson and Keggin-type clusters and were characterized by analytical and spectroscopic techniques including ESI-MS and/or single-crystal X-ray diffraction analyses. Radical initiated polymerization of 2 and 5 with organic monomers (methacryloyloxy)phenyldimethylsulfonium triflate (MAPDST) and/or methylmethacrylate (MMA) yielded a new series of POM/polymer hybrids that were characterized by (1) H, (31) P NMR and IR spectroscopic techniques, gel-permeation chromatography as well as thermal analyses. Preliminary tests were conducted on these POM/polymer hybrids to evaluate their properties as photoresists using electron beam (E-beam)/extreme ultraviolet (EUV) lithographic techniques. It was observed that the POM/polymer hybrid of 2 with MAPDST exhibited improved sensitivity under EUV lithographic conditions in comparison to the MAPDST homopolymer resist possibly due to the efficient photon harvesting by the POM clusters from the EUV source.

PECVD based silicon oxynitride thin films for nano photonic on chip interconnects applications.

Thin silicon oxynitride (SiO(x)N(y)) films were deposited by low temperature (~300°C) plasma enhanced chemical vapour deposition (PECVD), using SiH(4), N(2)O, NH(3) precursor of the flow rate 25, 100, 30 sccm and subjected to the post deposition annealing (PDA) treatment at 400°C and 600°C for nano optical/photonics on chip interconnects applications. AFM result reveals the variation of roughness from 60.9 Å to 23.4 Å after PDA treatment with respect to the as-deposited films, favourable surface topography for integrated waveguide applications. A model of decrease in island height with the effect of PDA treatment is proposed in support of AFM results. Raman spectroscopy and FTIR measurements are performed in order to define the change in crystallite and chemical bonding of as-deposited as well as PDA treated samples. These outcomes endorsed to the densification of SiO(x)N(y) thin films, due to decrease in Si-N and Si-O bonds strain, as well the O-H, N-H bonds with in oxynitride network. The increase in refractive index and PL intensity of as deposited SiO(x)N(y) thin films to the PDA treated films at 400°C and 600°C are observed. The significant shift of PL spectra peak positions indicate the change in cluster size as the result of PDA treatment, which influence the optical properties of thin films. It might be due to out diffusion of hydrogen containing species from silicon oxynitride films after PDA treatment. In this way, the structural and optical, feasibility of SiO(x)N(y) films are demonstrated in order to obtain high quality thin films for nano optical/photonics on chip interconnects applications.

Stability and dewetting of metal nanoparticle filled thin polymer films: control of instability length scale and dynamics.

We investigate the influence of gold nanoparticle addition on the stability, dewetting, and pattern formation in ultrathin polymer-nanoparticle (NP) composite films by examining the length and time scales of instability, morphology, and dynamics of dewetting. For these 10-50 nm thick (h) polystyrene (PS) thin films containing uncapped gold nanoparticles (diameter approximately 3-4 nm), transitions from complete dewetting to arrested dewetting to absolute stability were observed depending on the concentration of the particles. Experiments show the existence of three distinct stability regimes: regime 1, complete dewetting leading to droplet formation for nanoparticle concentration of 2% (w/w) or below; regime 2, partial dewetting leading to formation of arrested holes for NP concentrations in the range of 3-6%; and regime 3, complete inhibition of dewetting for NP concentrations of 7% and above. Major results are (a) length scale of instability, where lambdaH approximately hn remains unchanged with NP concentration in regime 1 (n approximately 2) but increases in regime 2 with a change in the scaling relation (n approximately 3-3.5); (b) dynamics of instability and dewetting becomes progressively sluggish with an increase in the NP concentration; (c) there are distinct regimes of dewetting velocity at low NP concentrations; (d) force modulation AFM, as well as micro-Raman analysis, shows phase separation and aggregation of the gold nanoparticles within each dewetted polymer droplet leading to the formation of a metal core-polymer shell morphology. The polymer shell could be removed by washing in a selective solvent, thus exposing an array of bare gold nanoparticle aggregates.

Templated one step electrodeposition of high aspect ratio n-type ZnO nanowire arrays.

High aspect ratio Zinc Oxide (ZnO) nanowires (NWs) were synthesized by template based one-step electrochemical deposition (OSECD) technique. The electro-reduction of hydroxide ions in the presence of Zn(2+) ions within Zn(NO(3))(2) is involved in the growth of ultra thin NWs arrays. Field Emission Scanning Electron Microscopy (FESEM) images revealed that the growth rates of different crystal faces, (0 0 0 1) and (0 0 0 1), were different at different deposition potential for the high aspect ratios ZnO NWs arrays. The n-type semiconductor conductivity of ZnO NWs was ascertained by a Hot-Probe approach. X-ray diffraction results demonstrated that the grown ZnO NWs had wurtzite crystal structure with unit cell parameters a=2.93 A, c=5.45 A and a deterioration of preferred (1 0 1) orientation is observed at more negative deposition potentials. Small angle X-ray scattering (SAXS) results evidenced that the NW arrays grown at -1.2 V have higher fraction of larger crystallites. Micro-Raman spectroscopy analysis showed that the variation in E(2) (high) vibration mode at 435 cm(-1) is coupled with an increase in electro acceptor oxygen atoms incorporated within ZnO NWs at -1.2 V.