Electrically tunable plasmonic behavior of nanocube-polymer nanomaterials induced by a redox-active electrochromic polymer
TL;DR: It is suggested that the combination of anisotropic nanostructures and electrochromic matrix has the potential to reversibly electrically tune plasmonic resonances over the full visible spectrum.
Abstract: We present a plasmon-active hybrid nanomaterial design with electrochemical tunability of the localized surface plasmon resonances. The plasmonic-active nanostructures are composed of silver nanocube aggregates embedded into an electrochromic polymer coating on an indium tin oxide electrode with the nanocube aggregation controlled by the surface pressure. Such polymer–nanocube hybrid nanomaterials demonstrated unique tunable plasmonic behavior under an applied electrochemical potential. A significant reversible experimental peak shift of 22 nm at an electrical potential of 200 mV has been achieved in these measurements. Finite-difference time-domain (FDTD) simulations show that, under full oxidation potential, a maximal spectral shift of ca. 80 nm can be potentially achieved, which corresponds to a high sensitivity of 178 nm per refractive index unit. Furthermore, FDTD modeling suggests that the electrochemically controlled tunability of plasmonic peaks is caused by reversible changes in the refractive in...
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TL;DR: The formation of submicrometre-scale structure in perovskite light-emitting diodes can raise their external quantum efficiency beyond 20%, suggesting the possibility of both high efficiency and high brightness.
Abstract: Light-emitting diodes (LEDs), which convert electricity to light, are widely used in modern society—for example, in lighting, flat-panel displays, medical devices and many other situations. Generally, the efficiency of LEDs is limited by nonradiative recombination (whereby charge carriers recombine without releasing photons) and light trapping1–3. In planar LEDs, such as organic LEDs, around 70 to 80 per cent of the light generated from the emitters is trapped in the device4,5, leaving considerable opportunity for improvements in efficiency. Many methods, including the use of diffraction gratings, low-index grids and buckling patterns, have been used to extract the light trapped in LEDs6–9. However, these methods usually involve complicated fabrication processes and can distort the light-output spectrum and directionality6,7. Here we demonstrate efficient and high-brightness electroluminescence from solution-processed perovskites that spontaneously form submicrometre-scale structures, which can efficiently extract light from the device and retain wavelength- and viewing-angle-independent electroluminescence. These perovskites are formed simply by introducing amino-acid additives into the perovskite precursor solutions. Moreover, the additives can effectively passivate perovskite surface defects and reduce nonradiative recombination. Perovskite LEDs with a peak external quantum efficiency of 20.7 per cent (at a current density of 18 milliamperes per square centimetre) and an energy-conversion efficiency of 12 per cent (at a high current density of 100 milliamperes per square centimetre) can be achieved—values that approach those of the best-performing organic LEDs. The formation of submicrometre-scale structure in perovskite light-emitting diodes can raise their external quantum efficiency beyond 20%, suggesting the possibility of both high efficiency and high brightness.
1,404 citations
Journal Article•
TL;DR: In this paper, the authors used electron beams instead of photons to detect plasmons as resonance peaks in the energy-loss spectra of sub-nanometre electron beams rastered on nanoparticles of well-defined geometrical parameters.
Abstract: Understanding how light interacts with matter at the nanometre scale is a fundamental issue in optoelectronics and nanophotonics. In particular, many applications (such as bio-sensing, cancer therapy and all-optical signal processing) rely on surface-bound optical excitations in metallic nanoparticles. However, so far no experimental technique has been capable of imaging localized optical excitations with sufficient resolution to reveal their dramatic spatial variation over one single nanoparticle. Here, we present a novel method applied on silver nanotriangles, achieving such resolution by recording maps of plasmons in the near-infrared/visible/ultraviolet domain using electron beams instead of photons. This method relies on the detection of plasmons as resonance peaks in the energy-loss spectra of subnanometre electron beams rastered on nanoparticles of well-defined geometrical parameters. This represents a significant improvement in the spatial resolution with which plasmonic modes can be imaged, and provides a powerful tool in the development of nanometre-level optics.
803 citations
Patent•
27 Mar 2014
TL;DR: By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organics layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathodes, and transmission of the injected electrons can also be performed with good efficiency as discussed by the authors.
Abstract: By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organic compound layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathode, and transmission of the injected electrons can be performed with good efficiency. Further, there are no problems such as excessive energy loss, deterioration of the organic compound layer itself, and the like accompanying electron movement, and therefore an increase in the electron injecting characteristics and a decrease in the driver voltage can both be achieved without depending on the work function of the cathode material.
236 citations
TL;DR: This work achieves fast, high-contrast electrochromic switching by significantly enhancing the interaction of light—propagating as deep-subwavelength-confined surface plasmon polaritons through arrays of metallic nanoslits, with an electrochrome polymer—present as an ultra-thin coating on the slit sidewalls.
Abstract: With vibrant colours and simple, room-temperature processing methods, electrochromic polymers have attracted attention as active materials for flexible, low-power-consuming devices. However, slow switching speeds in devices realized to date, as well as the complexity of having to combine several distinct polymers to achieve a full-colour gamut, have limited electrochromic materials to niche applications. Here we achieve fast, high-contrast electrochromic switching by significantly enhancing the interaction of light--propagating as deep-subwavelength-confined surface plasmon polaritons through arrays of metallic nanoslits, with an electrochromic polymer--present as an ultra-thin coating on the slit sidewalls. The switchable configuration retains the short temporal charge-diffusion characteristics of thin electrochromic films, while maintaining the high optical contrast associated with thicker electrochromic coatings. We further demonstrate that by controlling the pitch of the nanoslit arrays, it is possible to achieve a full-colour response with high contrast and fast switching speeds, while relying on just one electrochromic polymer.
209 citations
Cites background from "Electrically tunable plasmonic beha..."
...and electrochemical tunability of localized surface plasmon resonances [20-22]....
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Journal Article•
179 citations
References
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TL;DR: In this paper, the optical constants for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV.
Abstract: The optical constants $n$ and $k$ were obtained for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV. The film-thickness range was 185-500 \AA{}. Three optical measurements were inverted to obtain the film thickness $d$ as well as $n$ and $k$. The estimated error in $d$ was \ifmmode\pm\else\textpm\fi{} 2 \AA{}, and that in $n$, $k$ was less than 0.02 over most of the spectral range. The results in the film-thickness range 250-500 \AA{} were independent of thickness, and were unchanged after vacuum annealing or aging in air. The free-electron optical effective masses and relaxation times derived from the results in the near infrared agree satisfactorily with previous values. The interband contribution to the imaginary part of the dielectric constant was obtained by subtracting the free-electron contribution. Some recent theoretical calculations are compared with the results for copper and gold. In addition, some other recent experiments are critically compared with our results.
17,509 citations
"Electrically tunable plasmonic beha..." refers methods in this paper
...We found amuch better agreement with our experimentally measured extinction spectra by using the permittivity from the CRC approximation instead of the more commonly used source from Johnson and Christy (JC).(57) The significant difference between JC and CRC is the lower imaginary part for the JC data....
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TL;DR: The most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows, are described and some relevant procedures of the software are carried out.
Abstract: In this work we briefly describe the most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows. The article is structured in three different sections: The introduction is a perspective on the importance of software on scanning probe microscopy. The second section is devoted to describe the general structure of the application; in this section the capabilities of WSXM to read third party files are stressed. Finally, a detailed discussion of some relevant procedures of the software is carried out.
6,996 citations
Book•
03 May 1988
TL;DR: In this article, surface plasmons on smooth surfaces were used for light scattering at rough surfaces without an ATR device, and surface plasmon on gratings for enhanced roughness.
Abstract: Surface plasmons on smooth surfaces.- Surface plasmons on surfaces of small roughness.- Surfaces of enhanced roughness.- Light scattering at rough surfaces without an ATR device.- Surface plasmons on gratings.- Conclusions.
4,890 citations
"Electrically tunable plasmonic beha..." refers background in this paper
...It is worth noting that only the polymer in close contact with the nanocube contributes to a plasmonic resonance shift, because of the well-known exponential decay of the SPR field.(43)...
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4,073 citations
TL;DR: In this paper, the surface plasmon absorption of noble metal nanoparticles was studied and the effects of size, shape, and composition on the plasman absorption maximum and its bandwidth were discussed.
Abstract: The field of nanoparticle research has drawn much attention in the past decade as a result of the search for new materials. Size confinement results in new electronic and optical properties, possibly suitable for many electronic and optoelectronic applications. A characteristic feature of noble metal nanoparticles is the strong color of their colloidal solutions, which is caused by the surface plasmon absorption. This article describes our studies of the properties of the surface plasmon absorption in metal nanoparticles that range in size between 10 and 100 nm. The effects of size, shape, and composition on the plasmon absorption maximum and its bandwidth are discussed. Furthermore, the optical response of the surface plasmon absorption due to excitation with femtosecond laser pulses allowed us to follow the electron dynamics (electron−electron and electron−phonon scattering) in these metal nanoparticles. It is found that the electron−phonon relaxation processes in nanoparticles, which are smaller than t...
3,635 citations