Quantifying self-absorption losses in luminescent solar concentrators

Kate, Otmar M. ten; Hooning, Koen; Kolk, Erik van der

doi:10.1364/ao.53.005238

Cited by 31 publications

(10 citation statements)

References 20 publications

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“…Conventional light-concentrator concepts consist of one-pigment composites in waveguiding materials such as poly(methyl methacrylate) and have several intrinsic loss mechanisms that quickly reduce their light-harvesting efficiency below 50%. Among the most important loss mechanisms of conventional concentrators are escape cone losses and reabsorption losses (24)(25)(26)(27)(28). Escape cone losses are due to preferential excitation of pigments with transition dipole moment orientations perpendicular to the waveguiding direction, resulting into reemission into directions not suitable for waveguiding.…”

mentioning

confidence: 99%

A new ultrafast energy funneling material harvests three times more diffusive solar energy for GaInP photovoltaics

Willich

Wegener

Vornweg

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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There is no theoretical limit in using molecular networks to harvest diffusive sun photons on large areas and funnel them onto much smaller areas of highly efficient but also precious energy-converting materials. The most effective concept reported so far is based on a pool of randomly oriented, light-harvesting donor molecules that funnel all excitation quanta by ultrafast energy transfer to individual light-redirecting acceptor molecules oriented parallel to the energy converters. However, the best practical light-harvesting system could only be discovered by empirical screening of molecules that either align or not within stretched polymers and the maximum absorption wavelength of the empirical system was far away from the solar maximum. No molecular property was known explaining why certain molecules would align very effectively whereas similar molecules did not. Here, we first explore what molecular properties are responsible for a molecule to be aligned. We found a parameter derived directly from the molecular structure with a high predictive power for the alignability. In addition, we found a set of ultrafast funneling molecules that harvest three times more energy in the solar’s spectrum peak for GaInP photovoltaics. A detailed study on the ultrafast dipole moment reorientation dynamics demonstrates that refocusing of the diffusive light is based on ∼15-ps initial dipole moment depolarization followed by ∼50-ps repolarization into desired directions. This provides a detailed understanding of the molecular depolarization/repolarization processes responsible for refocusing diffusively scattered photons without violating the second law of thermodynamics.

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confidence: 99%

A new ultrafast energy funneling material harvests three times more diffusive solar energy for GaInP photovoltaics

Willich

Wegener

Vornweg

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…Note that the PL photons from Coumarin 6 can excite Lumogen F Red 305. 19,20 The concentrations of Coumarin 6 and Lumogen F Red 305 were 0.07 and 0.01 wt. %, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…For example, these spectra for the organic dyes we used in our experiments are found in the literatures. 19,20 Now, we try to relate I 2 ∕I 1 to the distance L. Setting the integration range to 630 nm < λ < 640 nm for Δλ SA and 650 nm < λ < 655 nm for Δλ NSA , we have calculated this index and the result is shown in Fig. 7.…”

Section: Linear Fluorescent Waveguidementioning

confidence: 99%

Position-sensitive detectors based on redshifts in photoluminescence spectra

2019

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We have proposed and demonstrated position-sensitive detectors based on the spectral changes in fluorescent waveguides. The first prototype is a transparent heat-shrink tubing containing an organic luminescent dye at its core. With a laser beam incident on this linear fluorescent tubing, the redshift in the photoluminescence (PL) spectrum observed at its edge increases with the distance from the incident point. The range for position sensing is 2 cm. It is extended to 280 cm by adopting a scintillating fiber in our second experiment. Two-stage conversion enables two-dimensional position detection. We have attached two linear fluorescent tubing to a planar 50 mm × 50 mm × 8 mm fluorescent waveguide. When a laser beam excites the first luminescent material at a single spot in the planer waveguide, PL photons propagate to its edges and excite the second luminescent material in the two linear waveguides. Photon division between these linear waveguides gives the first coordinate. The second coordinate is given by the redshift in the linear waveguides. We have observed that the maximum error in position estimation is 1.5 mm. Unlike the conventional semiconductor technologies, no electronic components are required for the sensor head. This robust technology might be suited for deployment in large-scale harsh environments. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…These include quantum dots, 25,26 quantum rods 27,28 and other materials. [29][30][31] Theoretical works on the efficiency of an LSC including self-absorption 32,33 and the effect of polarization 34 have been reported. The idea of patterning a phosphor layer has been studied for reducing self-absorption.…”

Section: Introductionmentioning

confidence: 99%

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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Quantifying self-absorption losses in luminescent solar concentrators

Cited by 31 publications

References 20 publications

A new ultrafast energy funneling material harvests three times more diffusive solar energy for GaInP photovoltaics

A new ultrafast energy funneling material harvests three times more diffusive solar energy for GaInP photovoltaics

Position-sensitive detectors based on redshifts in photoluminescence spectra

Angle-resolved photoluminescence spectrum of a uniform phosphor layer

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