Au–WS₂ Nanohybrids with Enhanced Optical Nonlinearity for Optical Limiting Applications

Abstract

Utilizing plasmonic effects of metal nanostructures on tailoring the properties of semiconducting materials has gained substantial research attention in the past 10 years. Here, we report the plasmon resonance-induced enhanced optical nonlinearity of Au−WS 2 nanohybrids prepared via the blending of liquid phase exfoliated few-layer WS 2 nanosheets with chemically synthesized spherical gold nanoparticles (NPs). Nonlinear optical properties were studied using the open aperture Z-scan technique with nanosecond laser pulses of wavelength 532 nm, which lie in the plasmonic band of Au NPs (480−550 nm) and B-excitonic transition range of WS 2 nanosheets (520−535 nm). Au−WS 2 nanohybrids exhibited an enhanced nonlinear absorption and optical limiting activity with an effective nonlinear absorption coefficient of 182 cm/GW at an on-axis input intensity of 0.14 GW/ cm 2 , which is 3.87 times higher than that of bare WS 2 nanosheets. The improved NLO response of nanohybrids is due to the plasmon resonance-induced local field effects, which significantly enhance B-excitonic transitions in WS 2 nanosheets. The simulated field intensity enhancement profile also confirmed the effect of formation, where a strong interaction of plasmonic fields with WS 2 nanosheets is clearly visible. The enhancement observed in simulated absorption density profiles indicated improved B-excitonic transitions in WS 2 nanosheets due to the resonant plasmonic field. Au−WS 2 nanohybrids exhibited a low limiting threshold of 0.55 J/cm 2 , which is better than that of many eminent nanohybrids reported so far. The strategy followed in this work for attaining superior nonlinear optical responses in Au−WS 2 nanohybrids will be useful to develop novel nonlinear optical materials for photonic device applications.

Enhancing saturable absorption in a Au-decorated MoS2/PEDOT:PSS nanocomposite through plasmon resonance and Pauli blocking

“…This nonlinear absorption coefficient is three orders of magnitude stronger than the reported value of Au/ZnO arrays 38 and six orders of magnitude stronger than comparative results reported in Au/WS 2 nanohybrids. 39 Saturable absorption is demonstrated by pure 2D MoS 2 , as confirmed by Wang et al, 40 and according to Abhijith et al 41 Au-WS 2 nanohybrids created by combining liquid-phase exfoliated few-layer WS 2 nanosheets with chemically generated spherical gold nanoparticles (NPs) exhibit improved optical nonlinearity induced by Plasmon resonance. They reported enhanced reverse saturable absorptions.…”

Synergistic Plasmonic Responses of Multi-Shaped Au Nanostructures Hybridized with Few-Layer WS2 Nanosheets for Organic Solar Cells

“…The selected area diffraction pattern (SAED) shown in the inset of Figure a confirms the polycrystalline nature of nanosheets. The detailed study on the morphology of WS 2 nanosheets, such as estimating the physical thickness, ensuring the uniform dispersity in thickness, and identifying the number of layers, were included in our earlier reports. , These studies revealed that present nanosheets exhibited a thickness around 2–4 nm that corresponds to a few layers, which is highly beneficial for utilizing these materials in the fabrication of OSCs, as reported by Lin et al Figure b,c shows the TEM and FE-SEM images of Au-WS 2 nanohybrids, respectively, where the WS 2 nanosheets were found to be uniformly decorated with the different shapes of isolated Au nanostructures.…”

Gold nanostructures/quantum dots for the enhanced efficiency of organic solar cells

“…Each Au nanostructure presented unique near-field effects, which significantly enhanced field intensity within the active layer. Additionally, more than 50% forward scattering occurred, making these plasmonic nanostructures suitable for enhancing photosensitivity and increasing absorption density in the system 22 . Loading mixed AuNPs, composed of bone-like rod shapes, cubes, and irregular spheres, into the PEDOT:PSS layer significantly improves the photovoltaic performance of the PTB7:PC 71 BM-based solar cell by 9.26%.…”

“…These nanostructures were strategically positioned not only within the active, hole transport, and buffer layers but also at their interfaces, leading to heightened solar cell efficiency. The utility of achieving multiple plasmonic excitations or tuning plasmonic activity has been demonstrated through the combination of different shapes of AuNPs [21][22][23]33 . Mixing shapes, such as spheres with rods, spheres with bipyramids, and hybrid configurations, have been reported, leveraging the cooperative effects of distinct plasmonic excitations arising from the combination of AuNP morphologies 20 .…”