Dye alignment in luminescent solar concentrators: I Vertical alignment for improved waveguide coupling

Mulder, Carlijn L.; Reusswig, Philip D.; Velazquez, Amador M.; Kim, Heekyung; Rotschild, Carmel; Baldo, Marc A.

doi:10.1364/oe.18.000a79

Cited by 114 publications

(117 citation statements)

References 23 publications

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“…Recent experimental [15][16][17][18][19] and theoretical [20] findings suggest that LSCs incorporating orientationally aligned dyes may improve performance by reducing escape-cone losses, and our detailed results below support this conclusion. Oriented LWs are important in other applications as well, such as liquid crystal lasers [21].…”

Section: Introductionsupporting

confidence: 77%

Comprehensive analysis of escape-cone losses from luminescent waveguides

et al. 2013

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Luminescent waveguides (LWs) occur in a wide range of applications, from solar concentrators to doped fiber amplifiers. Here we report a comprehensive analysis of escape-cone losses in LWs, which are losses associated with internal rays making an angle less than the critical angle with a waveguide surface. For applications such as luminescent solar concentrators, escape-cone losses often dominate all others. A statistical treatment of escape-cone losses is given accounting for photoselection, photon polarization, and the Fresnel relations, and the model is used to analyze light absorption and propagation in waveguides with isotropic and orientationally aligned luminophores. The results are then compared to experimental measurements performed on a fluorescent dye-doped poly(methyl methacrylate) waveguide.

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Section: Introductionsupporting

confidence: 77%

Comprehensive analysis of escape-cone losses from luminescent waveguides

et al. 2013

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“…Lower absorption naturally leads to lower edge emission, although the trapping efficiency of emitted photons increases from ≈65% to over 80% when vertically aligned luminophores in LSCs are excited by an isotropic light source. [62,63] The efficiency of transmission of the emitted photons to the edge of the waveguide can increase with close-to homeotropic alignment, as the path length through the luminophore-containing region of the thin absorbing/emitting layer is minimized. [64] Completely homeotropic alignment, however, could be detrimental, as most of the emitted light would be directed within the thin luminophore layer, and would result in excessive re-absorption events.…”

Section: Aligned Luminophoresmentioning

confidence: 99%

Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment

Debije

Verbunt

2011

Advanced Energy Materials

804

689

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Research on the luminescent solar concentrator (LSC) over the past thirty‐odd years is reviewed. The LSC is a simple device at its heart, employing a polymeric or glass waveguide and luminescent molecules to generate electricity from sunlight when attached to a photovoltaic cell. The LSC has the potential to find extended use in an area traditionally difficult for effective use of regular photovoltaic panels: the built environment. The LSC is a device very flexible in its design, with a variety of possible shapes and colors. The primary challenge faced by the devices is increasing their photon‐to‐electron conversion efficiencies. A number of laboratories are working to improve the efficiency and lifetime of the LSC device, with the ultimate goal of commercializing the devices within a few years. The topics covered here relate to the efforts for reducing losses in these devices. These include studies of novel luminophores, including organic fluorescent dyes, inorganic phosphors, and quantum dots. Ways to limit the surface and internal losses are also discussed, including using organic and inorganic‐based selective mirrors which allow sunlight in but reflect luminophore‐emitted light, plasmonic structures to enhance emissions, novel photovoltaics, alignment of the luminophores to manipulate the path of the emitted light, and patterning of the dye layer to improve emission efficiency. Finally, some possible ‘glimpses of the future’ are offered, with additional research paths that could result in a device that makes solar energy a ubiquitous part of the urban setting, finding use as sound barriers, bus‐stop roofs, awnings, windows, paving, or siding tiles.

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“…Denoting the critical angle for TIR as θ c , the trapping probability in cylindrical geometry is given by cosθ c for isotropic emission. 36 Hence, the trapped PL flux can be expressed as I wg = (I b + I f )cosθ c . This flux is disrupted by scattering events while it propagates inside.…”

Section: A Scattering Mediummentioning

confidence: 99%

“…This has been modeled by means of aligned electric dipoles. 36 Second, absorption of a polarized light by such dye molecules is anisotropic. It has been proposed to utilize horizontally-aligned dye molecules as a linear polarizer.…”

Section: B Anisotropic Mediummentioning

confidence: 99%

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Angle-resolved photoluminescence spectrum of a uniform phosphor layer

Fujieda

Ohta

2017

AIP Advances

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A photoluminescence spectrum depends on an emission angle due to self-absorption in a phosphor material. Assuming isotropic initial emission and Lambert-Beer’s law, we have derived simple expressions for the angle-resolved spectra emerging from the top and bottom surfaces of a uniform phosphor layer. The transmittance of an excitation light through the phosphor layer can be regarded as a design parameter. For a strongly-absorbing phosphor layer, the forward flux is less intense and more red-shifted than the backward flux. The red-shift is enhanced as the emission direction deviates away from the plane normal. When we increase the transmittance, the backward flux decreases monotonically. The forward flux peaks at a certain transmittance value. The two fluxes become similar to each other for a weakly-absorbing phosphor layer. We have observed these behaviors in experiment. In a practical application, self-absorption decreases the efficiency of conversion and results in angle-dependent variations in chromaticity coordinates. A patterned phosphor layer with a secondary optical element such as a remote reflector alleviates these problems.

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Dye alignment in luminescent solar concentrators: I Vertical alignment for improved waveguide coupling

Cited by 114 publications

References 23 publications

Comprehensive analysis of escape-cone losses from luminescent waveguides

Comprehensive analysis of escape-cone losses from luminescent waveguides

Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment

Angle-resolved photoluminescence spectrum of a uniform phosphor layer

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