Strong anisotropic influence of local-field effects on the dielectric response of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>-MoO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>

Lajaunie, Luc; Boucher, Florent; Dessapt, Rémi; Moreau, Philippe

doi:10.1103/physrevb.88.115141

Cited by 100 publications

(62 citation statements)

References 77 publications

(105 reference statements)

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“…The inner Ag layer, however, was modified to 35 nm in order to model the experimental modification described above. Transfer matrix calculations for the OPVs were performed using tabulated optical constants of PTB7-Th:PC 71 BM, [26] MoO 3 , [27] ZnO, [28] and ITO. [29] As shown in Figure 3a, the transmission efficiency of the device as a function of TiO x thickness and wavelength displays a dispersion characteristic that closely resembles that of the pure CF (Figure 2a) despite the 10 nm increase in inner Ag layer thickness and addition of high-index dielectric media.…”

Section: Wwwadvopticalmatdementioning

confidence: 99%

Semitransparent Blue, Green, and Red Organic Solar Cells Using Color Filtering Electrodes

Kim

Son

Shafian

et al. 2018

Advanced Optical Materials

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protocols that tailor the absorption spectrum of the active material. [1][2][3][4][5][6] While such efforts have resulted in a library of active materials, they have also presented challenges for commercial viability due to the different processes and costs associated with employing distinct active materials to display different colors. Their use has also resulted in varied performances among devices of different colors, adding to the difficulty for practical implementation. Furthermore, challenges in organic synthesis have limited the achievable types of color and their spectral purity. In this work, we introduce a strategy that enables a single active material that absorbs uniformly across the visible range to display different colors with high spectral purity and consistent device performances through the implementation of a color filtering (CF) electrode. The electrode consists of a Ag-TiO x -Ag Fabry-Perot (FP) resonant cavity, where the thickness of the TiO x layer determines the spectral position of the transmission peak and the inner Ag layer functions as an electrical contact. The electrode also functions as a mirror for all wavelengths of light except that within the resonant band (i.e., the spectral transparency window) of the CF. Therefore, light that has not been selectively transmitted may reflect back into the active material, contributing to additional charge generation. This implies that the short-circuit current density, which is largely a function of the optical absorption, must be higher for a CF-integrated OPV compared to a transparent OPV, under the condition that the two devices show similar peak transmission efficiencies.The use of photonic structures as optical filters in OPVs or inorganic solar cells has been previously reported in the form of distributed Bragg reflectors, [7][8][9] photonic arrays, [10][11][12] and plasmonic resonators. [13][14][15] While such filters enable various colors to be transmitted or reflected through tuning of the characteristic dimension of the filter components, in many cases they suffer from increased fabrication costs and duration because of the structural complexity. Moreover, photonic structures employing low-loss dielectrics exhibit poor electrical conductivity, precluding their use as an electrode. Finally, the structural anisotropy intrinsic to 1D or 3D photonic structures can result in asymmetric responses for light incident from above and below the device. Such behavior can complicate design schemes for creating bidirectional colored windows.Colorful, semitransparent organic photovoltaic cells (OPVs) are increasing in demand due to their applicability in aesthetically fashioned powergenerating windows. The traditional method of generating different colors in OPVs has been through employing different active materials exhibiting distinct absorption spectra. This can complicate fabrication processes for production and cause deviations in device performance among differently colored OPVs. Herein, semitransparent and colorful OPVs with a single broadban...

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Section: Wwwadvopticalmatdementioning

confidence: 99%

Semitransparent Blue, Green, and Red Organic Solar Cells Using Color Filtering Electrodes

Kim

Son

Shafian

et al. 2018

Advanced Optical Materials

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“…Low-loss EELS spectra contain many excitation processes including volume and surface plasmons, interband transitions and semi-core states transitions which can confound the identification of specific features (Garcia de Abajo, 2010; Lajaunie et al, 2013;Moreau & Boucher, 2012). XAS and core-loss EELS spectra are also not simple -ionization edges can overlap (Hakouk et al, 2013;Panchakarla et al, 2015) and the physical phenomena behind the white line intensity ratio and near-edge fine structures are highly complex (Krüger, 2010;Mizoguchi et al, 2010;Arenal et al, 2014b;Lajaunie et al, 2015;).…”

Section: Introductionmentioning

confidence: 99%

“…Low-loss EELS spectra can be used to determine the dielectric function, the plasmonic properties, the Young's modulus and for strain mapping of both nanostructures and bulk materials ( Oleshko & Howe, 2007;Arenal et al, 2008;Gu et al, 2010;Oleshko, 2012;Lajaunie et al, 2013;Arenal et al, 2014a).…”

Section: Introductionmentioning

confidence: 99%

A Complete Overhaul of the Electron Energy-Loss Spectroscopy and X-Ray Absorption Spectroscopy Database: eelsdb.eu

Ewels

Sikora²,

Serin

et al. 2016

Microsc Microanal

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The Electron Energy-Loss Spectroscopy (EELS) and X-ray Absorption Spectroscopy (XAS) database has been completely rewritten, with an improved design, user interface and a 3 number of new tools. The database is accessible at https://eelsdb.eu/ and can now be used without registration. The submission process has been streamlined to encourage spectrum submissions and the new design gives greater emphasis on contributors' original work by highlighting their papers. With numerous new filters and a powerful search function, it is now simple to explore the database of several hundred of EELS and XAS spectra. Interactive plots allow spectra to be overlaid, facilitating online comparison. An application-programming interface has been created, allowing external tools and software to easily access the information held within the database. In addition to the database itself, users can post and manage job adverts and read the latest news and events regarding the EELS and XAS communities. In accordance with the ongoing drive towards open access data increasingly demanded by funding bodies, the database will facilitate open access data sharing of EELS and XAS spectra.

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“…Larger or smaller values of n were unable to effectively reproduce the energy 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 5 variation of α′ IS over the measured energy range, with the most pronounced differences at energies above 1.5 eV. Although n has not previously been measured for these complex semiconductors, the refined values of n fall between those measured over the energy range of 0.5 -3.0 eV for the binary end members of La 2 O 3 (1.70 -1.75) 20 and MoO 3 (2.07 -2.32) 21 . This suggests that this novel self-referenced method is able to provide reasonable experimental estimates of the refractive indices of complex solids.…”

Section: Resultsmentioning

confidence: 55%

Self-Referenced Method for Estimating Refractive Index and Absolute Absorption of Loose Semiconductor Powders

et al. 2017

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The absolute absorption coefficient, α(E), is a critical design parameter for devices using semiconductors for light harvesting associated with renewable energy production, both for classic technologies like photovoltaics and for emerging technologies such as direct solar fuel production. While α(E) is well-known for many classic simple semiconductors used in photovoltaic applications, the absolute values of α(E) are typically unknown for the complex semiconductors being explored for solar fuel production due to the absence of single crystals or crystalline epitaxial films that are needed for conventional methods of determining α(E). In this work, a simple self-referenced method for estimating both the refractive indices, n(E), and absolute absorption coefficients, α(E), for loose powder samples using diffuse reflectance data is demonstrated. In this method, the sample refractive index can be deduced by refining n to maximize the agreement between the relative absorption spectrum calculated from bidirectional reflectance data (calculated through a Hapke transform which depends on n) and integrating sphere diffuse reflectance data (calculated through a Kubleka-Munk transform which does not depend on n). This new method can be quickly used to screen the suitability of emerging semiconductor systems for light-harvesting applications. The effectiveness of this approach is tested using the simple classic semiconductors Ge and Fe 2 O 3 as well as the complex semiconductors La 2 MoO 5 and La 4 Mo 2 O 11 . The method is shown to work well for powders with a narrow size distribution (exemplified by Fe 2 O 3 ) and to be ineffective for semiconductors with a broad size distribution (exemplified by Ge). As such, it provides a means for rapidly estimating the absolute optical properties of complex solids which are only available as loose powders.

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Strong anisotropic influence of local-field effects on the dielectric response ofα-MoO3

Cited by 100 publications

References 77 publications

Semitransparent Blue, Green, and Red Organic Solar Cells Using Color Filtering Electrodes

Semitransparent Blue, Green, and Red Organic Solar Cells Using Color Filtering Electrodes

A Complete Overhaul of the Electron Energy-Loss Spectroscopy and X-Ray Absorption Spectroscopy Database: eelsdb.eu

Self-Referenced Method for Estimating Refractive Index and Absolute Absorption of Loose Semiconductor Powders

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