Plasmonic absorption enhancement in organic solar cells with thin active layers
TL;DR: In this article, the influence of silver nanoparticles on light absorption in organic solar cells based on poly(3-exylthiophene):(6,6)-phenyl-C61-butyric-acid-methyl ester is studied by means of finite element method simulations.
Abstract: The influence of silver nanoparticles on light absorption in organic solar cells based on poly(3-exylthiophene):(6,6)-phenyl-C61-butyric-acid-methyl ester is studied by means of finite element method simulations. The metallic nanoparticles are embedded directly inside the active layer. We investigate the enhancement mechanism and the influence of factors such as the spacing between neighboring nanoparticles, the particle diameter, and the coating thickness. The plasmonic resonance of the particles has a wideband influence on the absorption, and we observe a rich interaction between plasmonic enhancement and the absorption characteristics of the active layer material. An enhancement with a factor of around 1.56 is observed for nanoparticles with a diameter of 24 nm and a spacing of 40 nm, bringing the structure to the absorption level of much thicker active layers without nanoparticles. In addition, a significant effect of the particle coating thickness is observed.
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TL;DR: In plasmonics, the metal nanostructures can serve as antennas to convert light into localized electric fields (E-fields) or as waveguides to route light to desired locations with nanometer precision through a strong interaction between incident light and free electrons in the nanostructure.
Abstract: Coinage metals, such as Au, Ag, and Cu, have been important materials throughout history.1 While in ancient cultures they were admired primarily for their ability to reflect light, their applications have become far more sophisticated with our increased understanding and control of the atomic world. Today, these metals are widely used in electronics, catalysis, and as structural materials, but when they are fashioned into structures with nanometer-sized dimensions, they also become enablers for a completely different set of applications that involve light. These new applications go far beyond merely reflecting light, and have renewed our interest in maneuvering the interactions between metals and light in a field known as plasmonics.2–6
In plasmonics, the metal nanostructures can serve as antennas to convert light into localized electric fields (E-fields) or as waveguides to route light to desired locations with nanometer precision. These applications are made possible through a strong interaction between incident light and free electrons in the nanostructures. With a tight control over the nanostructures in terms of size and shape, light can be effectively manipulated and controlled with unprecedented accuracy.3,7 While many new technologies stand to be realized from plasmonics, with notable examples including superlenses,8 invisible cloaks,9 and quantum computing,10,11 conventional technologies like microprocessors and photovoltaic devices could also be made significantly faster and more efficient with the integration of plasmonic nanostructures.12–15 Of the metals, Ag has probably played the most important role in the development of plasmonics, and its unique properties make it well-suited for most of the next-generation plasmonic technologies.16–18
1.1. What is Plasmonics?
Plasmonics is related to the localization, guiding, and manipulation of electromagnetic waves beyond the diffraction limit and down to the nanometer length scale.4,6 The key component of plasmonics is a metal, because it supports surface plasmon polariton modes (indicated as surface plasmons or SPs throughout this review), which are electromagnetic waves coupled to the collective oscillations of free electrons in the metal.
While there are a rich variety of plasmonic metal nanostructures, they can be differentiated based on the plasmonic modes they support: localized surface plasmons (LSPs) or propagating surface plasmons (PSPs).5,19 In LSPs, the time-varying electric field associated with the light (Eo) exerts a force on the gas of negatively charged electrons in the conduction band of the metal and drives them to oscillate collectively. At a certain excitation frequency (w), this oscillation will be in resonance with the incident light, resulting in a strong oscillation of the surface electrons, commonly known as a localized surface plasmon resonance (LSPR) mode.20 This phenomenon is illustrated in Figure 1A. Structures that support LSPRs experience a uniform Eo when excited by light as their dimensions are much smaller than the wavelength of the light.
Figure 1
Schematic illustration of the two types of plasmonic nanostructures discussed in this article as excited by the electric field (Eo) of incident light with wavevector (k). In (A) the nanostructure is smaller than the wavelength of light and the free electrons ...
In contrast, PSPs are supported by structures that have at least one dimension that approaches the excitation wavelength, as shown in Figure 1B.4 In this case, the Eo is not uniform across the structure and other effects must be considered. In such a structure, like a nanowire for example, SPs propagate back and forth between the ends of the structure. This can be described as a Fabry-Perot resonator with resonance condition l=nλsp, where l is the length of the nanowire, n is an integer, and λsp is the wavelength of the PSP mode.21,22 Reflection from the ends of the structure must also be considered, which can change the phase and resonant length. Propagation lengths can be in the tens of micrometers (for nanowires) and the PSP waves can be manipulated by controlling the geometrical parameters of the structure.23
2,421 citations
TL;DR: The benefits of using various plasmonic nanostructures for broad-band, polarization-insensitive and angle-independent absorption enhancement, and their integration with one or two electrode(s) of an OPV device are discussed.
Abstract: Recent advances in molecular organic photovoltaics (OPVs) have shown 10% power conversion efficiency (PCE) for single-junction cells, which put them in direct competition with PVs based on amorphous silicon. Incorporation of plasmonic nanostructures for light trapping in these thin-film devices offers an attractive solution to realize higher-efficiency OPVs with PCE>>10%. This article reviews recent progress on plasmonic-enhanced OPV devices using metallic nanoparticles, and one-dimensional (1D) and two-dimensional (2D) patterned periodic nanostructures. We discuss the benefits of using various plasmonic nanostructures for broad-band, polarization-insensitive and angle-independent absorption enhancement, and their integration with one or two electrode(s) of an OPV device.
460 citations
TL;DR: In this paper, the authors highlight the different strategies of incorporating plasmonic NPs for light trapping into either the active or buffer layer or at various interfaces within the OPV cell architecture.
380 citations
TL;DR: In this article, the authors investigated the optical and electrical properties of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) layer and showed that the very strong near field around Au nanoparticles due to Localized Surface Plasmonic Resonance (LSPR) mainly distributes laterally along the PEDOT-PSS layer rather than vertically into the adjacent active layer, leading to minimal enhancement of light absorption in the active layer.
Abstract: We unveil new device physics and provide details of device mechanisms by investigating polymer solar cells (PSCs) incorporating Au nanoparticles (NPs) into the hole collection poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) layer Theoretical and experimental results show that the very strong near field around Au NPs due to Localized Surface Plasmonic Resonance (LSPR) mainly distributes laterally along the PEDOT:PSS layer rather than vertically into the adjacent active layer, leading to minimal enhancement of light absorption in the active layer This finding can be extended to a typical class of solar cells incorporating metallic NPs in spacing layers adjacent to the active layer With optical effects proven to be minor contributors to device performance improvements, we investigate the electrical properties of the PSCs and obtain insights into the detailed device mechanisms Improvements in power conversion efficiency (PCE) of solar cells are found to originate from the enlarged active layer/PEDOT:PSS interfacial area and improved PEDOT:PSS conductivity At high NP concentrations, reduced exciton quenching at donor/acceptor junctions is found to cause PCE deterioration Our findings indicate that it is highly important to investigate both optical and electrical effects for understanding and optimizing PSC performances
271 citations
TL;DR: Two of the recent major research topics in optoelectronic devices are discussed: the development of new organic materials for the active layer of organic optoelected devices (particularly organic light-emitting diodes (OLEDs)), and light management, including light extraction for OLEDs and light trapping for organic solar cells (OSCs).
Abstract: Two of the recent major research topics in optoelectronic devices are discussed: the development of new organic materials (both molecular and polymeric) for the active layer of organic optoelectronic devices (particularly organic light-emitting diodes (OLEDs)), and light management, including light extraction for OLEDs and light trapping for organic solar cells (OSCs). In the first section, recent developments of phosphorescent transition metal complexes for OLEDs in the past 3–4 years are reviewed. The discussion is focused on the development of metal complexes based on iridium, platinum, and a few other transition metals. In the second part, different light-management strategies in the design of OLEDs with improved light extraction, and of OSCs with improved light trapping is discussed.
261 citations
References
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12 Jul 1985
TL;DR: In this paper, E.D. Palik and R.R. Potter, Basic Parameters for Measuring Optical Properties, and W.W.Hunter, Measurement of Optical Constants in the Vacuum Ultraviolet Spectral Region.
Abstract: VOLUME ONE: Determination of Optical Constants: E.D. Palik, Introductory Remarks. R.F. Potter, Basic Parameters for Measuring Optical Properties. D.Y. Smith, Dispersion Theory, Sum Rules, and Their Application to the Analysis of Optical Data. W.R. Hunter, Measurement of Optical Constants in the Vacuum Ultraviolet Spectral Region. D.E. Aspnes, The Accurate Determination of Optical Properties by Ellipsometry. J. Shamir, Interferometric Methods for the Determination of Thin-Film Parameters. P.A. Temple, Thin-Film Absorplance Measurements Using Laser Colorimetry. G.J. Simonis, Complex Index of Refraction Measurements of Near-Millimeter Wavelengths. B. Jensen, The Quantum Extension of the Drude--Zener Theory in Polar Semiconductors. D.W. Lynch, Interband Absorption--Mechanisms and Interpretation. S.S. Mitra, Optical Properties of Nonmetallic Solids for Photon Energies below the Fundamental Band Gap. Critiques--Metals: D.W. Lynch and W.R. Hunter, Comments of the Optical Constants of Metals and an Introduction to the Data for Several Metals. D.Y. Smith, E. Shiles, and M. Inokuti, The Optical Properties of Metallic Aluminum. Critiques--Semiconductors: E.D. Palik, Cadium Telluride (CdTe). E.D. Palik, Gallium Arsenide (GaAs). A. Borghesi and G. Guizzetti, Gallium Phosphide (GaP). R.F. Potter, Germanium (Ge). E.D. Palik and R.T. Holm, Indium Arsenide (InAs). R.T. Holm, Indium Antimonide (InSb). O.J. Glembocki and H. Piller, Indium Phosphide (InP). G. Bauer and H. Krenn, Lead Selenide (PbSe). G. Guizzetti and A. Borghesi, Lead Sulfide (PbS). G. Bauer and H. Krenn, Lead Telluride (PbTe). D.F. Edwards, Silicon (Si). H. Piller, Silicon (Amorphous) (-Si). W.J. Choyke and E.D. Palik, Silicon Carbide (SiC). E.D. Palik and A. Addamiano, Zinc Sulfide (ZnS). Critiques--Insulators: D.J. Treacy, Arsenic Selenide (As 2 gt Se 3 gt ). D.J. Treacy, Arsenic Sulfide (As 2 gt S 3 gt ). D.F. Edwards and H.R. Philipp, Cubic Carbon (Diamond). E.D. Palik and W.R. Hunter, Litium Fluoride (LiF). E.D. Palik, Lithium Niobote (LiNbO 3 gt ). E.D. Palik, Potassium Chloride (KCl). H.R. Philipp, Silicon Dioxide (SiO 2 gt ), Type ( (Crystalline). H.R. Philipp, Silicon Dioxide (SiO 2 gt ) (Glass). gt H.R. Philipp, Silicon Monoxide (SiO) (Noncrystalline). H.R. Philipp, Silicon Nitride (Si 3 gt N 4 gt ) (Noncrystalline). J.E. Eldridge and E.D. Palik, Sodium Chloride (NaCl). M.W. Ribarsky, Titanium Dioxide (TiO 2 gt ) (Rutile).
17,491 citations
TL;DR: In this paper, the carrier collection efficiency and energy conversion efficiency of polymer photovoltaic cells were improved by blending of the semiconducting polymer with C60 or its functionalized derivatives.
Abstract: The carrier collection efficiency (ηc) and energy conversion efficiency (ηe) of polymer photovoltaic cells were improved by blending of the semiconducting polymer with C60 or its functionalized derivatives. Composite films of poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) and fullerenes exhibit ηc of about 29 percent of electrons per photon and ηe of about 2.9 percent, efficiencies that are better by more than two orders of magnitude than those that have been achieved with devices made with pure MEH-PPV. The efficient charge separation results from photoinduced electron transfer from the MEH-PPV (as donor) to C60 (as acceptor); the high collection efficiency results from a bicontinuous network of internal donor-acceptor heterojunctions.
9,611 citations
Book•
05 Oct 2014
TL;DR: In this paper, the authors present a survey of optical spectra of Elemental Metal Clusters and Chain Aggregates and discuss experimental results and experimental methods for metal clustering experiments.
Abstract: 1. Introduction.- 2. Theoretical Considerations.- 3. Experimental Methods.- 4. Experimental Results and Discussion.- A.1 Tables: Optical Spectroscopy Experiments with Metal Clusters.- A.2 Survey of Optical Spectra of Elemental Metal Clusters and Chain-Aggregates.- A.3 Mie Computer Program.- References.
6,405 citations
TL;DR: In this paper, a polymer solar cell based on a bulk hetereojunction design with an internal quantum efficiency of over 90% across the visible spectrum (425 nm to 575 nm) is reported.
Abstract: A polymer solar-cell based on a bulk hetereojunction design with an internal quantum efficiency of over 90% across the visible spectrum (425 nm to 575 nm) is reported. The device exhibits a power-conversion efficiency of 6% under standard air-mass 1.5 global illumination tests.
4,002 citations
Book•
01 Jan 2006TL;DR: In this paper, the authors proposed a method for propagating and focusing of optical fields in a nano-optics environment using near-field optical probes and probe-sample distance control.
Abstract: 1. Introduction 2. Theoretical foundations 3. Propagation and focusing of optical fields 4. Spatial resolution and position accuracy 5. Nanoscale optical microscopy 6. Near-field optical probes 7. Probe-sample distance control 8. Light emission and optical interaction in nanoscale environments 9. Quantum emitters 10. Dipole emission near planar interfaces 11. Photonic crystals and resonators 12. Surface plasmons 13. Forces in confined fields 14. Fluctuation-induced phenomena 15. Theoretical methods in nano-optics Appendices Index.
3,772 citations