skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Hybrid Metal–Ligand Interfacial Dipole Engineering of Functional Plasmonic Nanostructures for Extraordinary Responses of Optoelectronic Properties
Title: Hybrid Metal–Ligand Interfacial Dipole Engineering of Functional Plasmonic Nanostructures for Extraordinary Responses of Optoelectronic Properties
Programmable manipulation of inorganic–organic interfacial electronic properties of ligand-functionalized plasmonic nanoparticles (NPs) is the key parameter dictating their applications such as catalysis, photovoltaics, and biosensing. Here we report the localized surface plasmon resonance (LSPR) properties of gold triangular nanoprisms (Au TNPs) in solid state that are functionalized with dipolar, conjugated ligands. A library of thiocinnamate ligands with varying surface dipole moments were used to functionalize TNPs, which results in ∼150 nm reversible tunability of LSPR peak wavelength with significant peak broadening (∼230 meV). The highly adjustable chemical system of thiocinnamate ligands is capable of shifting the Au work function down to 2.4 eV versus vacuum, i.e., ∼2.9 eV lower than a clean Au (111) surface, and this work function can be modulated up to 3.3 eV, the largest value reported to date through the formation of organothiolate SAMs on Au. Interestingly, the magnitude of plasmonic responses and work function modulation is NP shape dependent. By combining first-principles calculations and experiments, we have established the mechanism of direct wave function delocalization of electrons residing near the Fermi level into hybrid electronic states that are mostly dictated by the inorganic–organic interfacial dipole moments. We determine that both interfacial dipole and hybrid electronic states, and vinyl conjugation together are the key to achieving such extraordinary changes in the optoelectronic properties of ligand-functionalized, plasmonic NPs. The present study provides a quantitative relationship describing how specifically constructed organic ligands can be used to control the interfacial properties of NPs and thus the plasmonic and electronic responses of these functional plasmonics for a wide range of plasmon-driven applications.  more » « less
Award ID(s):
2204681
PAR ID:
10521596
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
American Chemical Society
Date Published:
Journal Name:
ACS Nano
Volume:
17
Issue:
17
ISSN:
1936-0851
Page Range / eLocation ID:
17499 to 17515
Subject(s) / Keyword(s):
gold nanoparticles localized surface plasmon resonance dipole moment surface passivating ligand inorganic−organic interface work function
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; (, Advanced Optical Materials)
    Abstract Plasmonic rulers (PRs) linking nanoscale distance dependence spectral shifts are important for studying cellular microenvironments and biomarker detection. The traditional PR design employs tethering metal nanoparticle pairs using synthetic and biopolymers that severely suffer from reproducibility issues, as well as lack reversibility. Here, the fabrication of novel PRs is reported through the formation of self‐assembled monolayers (SAMs) of photoswitchable molecular machines chemically tethered onto sharp‐tip gold nanostructures (Au NSs). This unique and highly sensitive PR utilizes localized surface plasmon resonance (LSPR) properties of Au NSs to spectroscopically evaluate dipole–dipole coupling between NSs and photoisomerizable spiropyran (SP)‐merocyanine (MC) conjugates in the solid‐state. It is observed that the SAM‐modified NSs are extremely sensitive to the photoisomerization of SP‐to‐MC, resulting in LSPR shifts as large as 5.6 nm for every 1.0 Å change in distance. The highly dipolar MC changes the NS‐SAM interfacial polarizability and alters the dipole–dipole coupling leading to the ultrasensitive PR is hypothesized. The hypothesis is supported theoretically by calculating dipole polarizability of an inorganic‐organic heterodimer model and experimentally by determining work function and interfacial dipole values. Taken together, this work represents the fabrication of next‐generation PRs, which hold great promise for advanced, plasmonic‐based sensors and optoelectronic device fabrication. 
    more » « less
  2. ; ; ; ; (, Advanced Photonics Research)
    Metal–semiconductor hybrid nanomaterials (HNMs) exhibit unique properties that are distinct from individual nanostructures, leading to promising applications in optical technologies. The interfacial linkage of semiconductor and metal nanoparticles (NPs) via cogelation is an effective strategy to produce HNMs that show strong plasmon‐exciton coupling and improved physical properties. However, optical properties of these hybrids show little to no tunability. Herein, CdSe/Ag hybrid aerogels that show tunable absorption and photoluminescence (PL) are produced by cogelation of CdSe nanorods (NRs) or NPs with Ag hollow NPs. Hybrid electronic states are created by overlapping the excitonic absorption of CdSe NRs or NPs with the plasmonic absorption of Ag NPs. Physical characterization of the hybrids reveals an interconnected network of hexagonal CdSe and cubic Ag NPs, linked by Ag+and Se2−surface species, without intervening ligands. PL spectra exhibit maxima at 640 and 720 nm for the CdSe NPs/Ag and CdSe NRs/Ag hybrids, respectively, corresponding to new radiative decay mechanisms. Time‐resolved PL data support the emergence of new radiative pathways, kinetically and energetically distinct from the excitonic and plasmonic properties of primary NPs. This new approach of metal–semiconductor hybrid formation through cogelation is intriguing for the design of high‐efficiency HNMs without detrimental PL quenching. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; (, Small)
    Abstract The in‐plane packing of gold (Au), polystyrene (PS), and silica (SiO2) spherical nanoparticle (NP) mixtures at a water–oil interface is investigated in situ by UV–vis reflection spectroscopy. All NPs are functionalized with carboxylic acid such that they strongly interact with amine‐functionalized ligands dissolved in an immiscible oil phase at the fluid interface. This interaction markedly increases the binding energy of these nanoparticle surfactants (NPSs). The separation distance between the Au NPSs and Au surface coverage are measured by the maximum plasmonic wavelength (λmax) and integrated intensities as the assemblies saturate for different concentrations of non‐plasmonic (PS/SiO2) NPs. As the PS/SiO2content increases, the time to reach intimate Au NP contact also increases, resulting from their hindered mobility. λmaxchanges within the first few minutes of adsorption due to weak attractive inter‐NP forces. Additionally, a sharper peak in the reflection spectrum at NP saturation reveals tighter Au NP packing for assemblies with intermediate non‐plasmonic NP content. Grazing incidence small angle X‐ray scattering (GISAXS) and scanning electron microscopy (SEM) measurements confirm a decrease in Au NP domain size for mixtures with larger non‐plasmonic NP content. The results demonstrate a simple means to probe interfacial phase separation behavior using in situ spectroscopy as interfacial structures densify into jammed, phase‐separated NP films. 
    more » « less
  4. ; ; ; ; (, Chemistry – A European Journal)
    Abstract Surface functionalization and colloidal stability are pivotal for numerous applications of gold nanoparticles (Au‐NPs). Over the past decade, N‐heterocyclic carbenes (NHCs) have emerged as promising ligands for stabilizing Au‐NPs owing to their ease of synthesis, structural diversity, and strong metal‐ligand bonds. Here, we introduce new Au(I)–NHCcopolymer scaffolds as precursors to multidentate NHC‐protected Au‐NPs. Ring‐opening metathesis copolymerization of a norbornene‐appended Au(I)−NHC complex with another functionalized norbornene comonomer provides NHC–Au(I) copolymers with modular compositions and structures. Upon reduction, these copolymers yield multidentate polyNHC‐coated Au‐NPs with varied properties and corona functionalities dictated by the secondary monomer. These nanoparticles exhibit excellent size homogeneity and stability against aggregation in various buffers, cell culture media, and under exposure to electrolytes, oxidants, and exogenous thiols over extended periods. Moreover, we demonstrate post‐synthetic surface functionalization reactions of polyNHC−Au‐NPs while maintaining colloidal stability, highlighting their robustness and potential for applications such as bioconjugation. Overall, these findings underscore the potential of ROMP‐derived NHC‐containing copolymers as highly tunable and versatile multidentate ligands that may be suitable for other inorganic colloids and flat surfaces. 
    more » « less
  5. ; ; ; ; ; ; ; ; ; (, Nanoscale Advances)
    Multiferroic materials are an interesting functional material family combining two ferroic orderings, e.g. , ferroelectric and ferromagnetic orderings, or ferroelectric and antiferromagnetic orderings, and find various device applications, such as spintronics, multiferroic tunnel junctions, etc. Coupling multiferroic materials with plasmonic nanostructures offers great potential for optical-based switching in these devices. Here, we report a novel nanocomposite system consisting of layered Bi 1.25 AlMnO 3.25 (BAMO) as a multiferroic matrix and well dispersed plasmonic Au nanoparticles (NPs) and demonstrate that the Au nanoparticle morphology and the nanocomposite properties can be effectively tuned. Specifically, the Au particle size can be tuned from 6.82 nm to 31.59 nm and the 6.82 nm one presents the optimum ferroelectric and ferromagnetic properties and plasmonic properties. Besides the room temperature multiferroic properties, the BAMO-Au nanocomposite system presents other unique functionalities including localized surface plasmon resonance (LSPR), hyperbolicity in the visible region, and magneto-optical coupling, which can all be effectively tailored through morphology tuning. This study demonstrates the feasibility of coupling single phase multiferroic oxides with plasmonic metals for complex nanocomposite designs towards optically switchable spintronics and other memory devices. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email