Metallic nanoparticles show extraordinary strong light absorption near their plasmon resonance, orders of magnitude larger compared to nonmetallic nanoparticles. This "antenna" effect has recently been exploited to transfer electrons into empty states of an attached material, for example to create electric currents in photovoltaic devices or to induce chemical reactions. It is generally assumed that plasmons decay into hot electrons, which then transfer to the attached material. Ultrafast electron-electron scattering reduces the lifetime of hot electrons drastically in metals and therefore strongly limits the efficiency of plasmon induced hot electron transfer. However, recent work has revived the concept of plasmons decaying directly into an interfacial charge transfer state, thus avoiding the intermediate creation of hot electrons. This direct decay mechanism has mostly been neglected, and has been termed chemical interface damping (CID). CID manifests itself as an additional damping contribution to the homogeneous plasmon line width. In this study, we investigate the size dependence of CID by following the plasmon line width of gold nanorods during the adsorption process of thiols on the gold surface with single particle spectroscopy. We show that CID scales inversely with the effective path length of electrons, i.e., the average distance of electrons to the surface. Moreover, we compare the contribution of CID to other competing plasmon decay channels and predict that CID becomes the dominating plasmon energy decay mechanism for very small gold nanorods.

Aluminum is abundant, low in cost, compatible with complementary metal-oxide semiconductor manufacturing methods, and capable of supporting tunable plasmon resonance structures that span the entire visible spectrum. However, the use of Al for color displays has been limited by its intrinsically broad spectral features. Here we show that vivid, highly polarized, and broadly tunable color pixels can be produced from periodic patterns of oriented Al nanorods. Whereas the nanorod longitudinal plasmon resonance is largely responsible for pixel color, far-field diffractive coupling is used to narrow the plasmon linewidth, enabling monochromatic coloration and significantly enhancing the far-field scattering intensity of the individual nanorod elements. The bright coloration can be observed with p-polarized white light excitation, consistent with the use of this approach in display devices. The resulting color pixels are constructed with a simple design, are compatible with scalable fabrication methods, and provide contrast ratios exceeding 100:1.RGB | chromaticity | array | electron beam lithography D isplay technologies have been evolving toward vivid, fullcolor, flat-panel displays with high resolution and/or small pixel sizes, higher energy efficiency, and improved benefit/cost ratios. Some of the most popular current technologies are liquid crystal displays (LCD), laser phosphor displays, also known as electroluminescent displays, and light-emitting diode (LED)-based displays. A common characteristic of all color display technologies is the incorporation of various color-producing media, which can be inorganic, organic, or polymeric materials, into the device. These chromatic materials are chosen to produce the fundamental components of the color spectrum in additive color schemes such as the standard red-green-blue (sRGB) when illuminated by an internal light source or when an electrical voltage is applied.Inorganic chromatic materials have the potential to greatly extend the durability and lifetime of color displays. Inorganic nanoparticles have recently begun to be used in color displays in the form of quantum dot LEDs, which have excellent display lifetimes and industry-scalable, size-based, and material-based color tunability (1-3). However, obtaining blue colors from quantum dots has been challenging (4) owing to the requirement of synthesizing nanoparticles in the small size range required to achieve optical transitions in this wavelength range. Au nanoparticles can produce green and red colors based on their surface plasmon resonances (5), but shorter-wavelength hues are quenched because of interband transitions for wavelengths below 520 nm (6). Ag has also been investigated for display applications (7, 8), but although spectral features can be achieved across the visible region the material readily oxidizes (9, 10), requiring additional passivation layers.Al is potentially a highly attractive material for plasmon-based full-spectrum displays. Al is the third most abundant element in the earth's crust, beh...

The chemical nature of surface adsorbates affects the localized surface plasmon resonance of metal nanoparticles. However, classical electromagnetic simulations are blind to this effect, whereas experiments are typically plagued by ensemble averaging that also includes size and shape variations. In this work, we are able to isolate the contribution of surface adsorbates to the plasmon resonance by carefully selecting adsorbate isomers, using single-particle spectroscopy to obtain homogeneous linewidths, and comparing experimental results to high-level quantum mechanical calculations based on embedded correlated wavefunction theory. Our approach allows us to indisputably show that nanoparticle plasmons are influenced by the chemical nature of the adsorbates 1,7-dicarbadodecaborane(12)-1-thiol (M1) and 1,7-dicarbadodecaborane(12)-9-thiol (M9). These surface adsorbates induce inside the metal electric dipoles that act as additional scattering centers for plasmon dephasing. In contrast, charge transfer from the plasmon to adsorbates—the most widely suggested mechanism to date—does not play a role here.

We compare the decay of plasmons and “conventional” hot electrons within the same series of gold/metal oxide interfaces. We found an accelerated decay of hot electrons at gold-metal oxide interfaces with decreasing band gap of the oxide material. The decay is accelerated by the increased phase space for electron scattering caused by additional interfacial states. Since plasmons decay faster within the same series of gold-metal oxide interfaces, we propose plasmons are able to decay into the same interfacial states as hot electrons. The similarity of plasmon damping to conventional hot electron decay implies that many classical surface analysis techniques and theoretical concepts are transferable to plasmonic systems. Our results support the mechanism of direct decay of plasmons into interfacial hot electron pairs but the utility of these interfacial states for charge transfer reactions remains to be investigated.

Plasmonic metal nanoparticles exhibit large dipole moments upon photoexcitation and have the potential to induce electronic transitions in nearby materials, but fast internal relaxation has to date limited the spatial range and efficiency of plasmonic mediated processes. In this work, we use photo-electrochemistry to synthesize hybrid nanoantennas comprised of plasmonic nanoparticles with photoconductive polymer coatings. We demonstrate that the formation of the conductive polymer is selective to the nanoparticles and that polymerization is enhanced by photoexcitation. In situ spectroscopy and simulations support a mechanism in which up to 50% efficiency of nonradiative energy transfer is achieved. These hybrid nanoantennas combine the unmatched light-harvesting properties of a plasmonic antenna with the similarly unmatched device processability of a polymer shell.