High-Efficiency Organic Solar Concentrators for Photovoltaics

Currie, Michael J.; Mapel, Jonathan K.; Heidel, T. D.; Goffri, Shalom; Baldo, Marc A.

doi:10.1126/science.1158342

Cited by 642 publications

(527 citation statements)

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“…Experimental realizations have demonstrated a twelve-fold concentration of solar flux [2] and power conversion efficiency of 7.2%, well below the theoretical predictions of a flux concentration in excess of 100 [3] and power conversion efficiency of 26.8% [4]. Reabsorption of luminescence and subsequent re-emission into non-waveguided modes has been identified as the primary performance bottleneck [5][6][7][8][9].…”

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Nanophotonic luminescent solar concentrators

Rousseau

Wood

2013

Applied Physics Letters

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We investigate the connection between photonic local density of states and luminescent solar concentrator (LSC) performance in two manufacturable nanocavity LSC structures, a bilayer slab and a slab photonic crystal. Finite-difference time-domain electromagnetic simulations show that the waveguided luminescence photon flux can be enhanced up to 30% for the photonic crystal design over a conventional LSC operating in the ray optic limit assuming the same number of excited lumophores. Further photonic engineering could realize an increase of up to one order of magnitude in the flux of waveguided luminescence.The luminescent solar concentrator (LSC) could decrease the installed cost of solar energy through building integration [1]. The LSC, a semi-transparent waveguide with embedded lumophores, concentrates sunlight by frequency downconversion; the lumophores absorb diffuse incident sunlight and luminesce at a redder, Stokesshifted wavelength. The majority of the luminescence is emitted into modes that can be guided by total internal reflection (TIR) to the waveguide edges, upon which small-area, high efficiency solar cells are normally fastened.Despite the LSC's simplicity, the concept has not been commercialized due to low performance. Experimental realizations have demonstrated a twelve-fold concentration of solar flux [2] and power conversion efficiency of 7.2%, well below the theoretical predictions of a flux concentration in excess of 100 [3] and power conversion efficiency of 26.8% [4]. Reabsorption of luminescence and subsequent re-emission into non-waveguided modes has been identified as the primary performance bottleneck [5][6][7][8][9].While prior work has demonstrated that LSCs consisting of lumophores embedded in optical nanocavities exhibit enhanced waveguiding [10] and reduced reabsorption [11], the nanocavity modifies the photonic local density of states (LDOS) and therefore the spatial and temporal luminescence distributations [12,13]. Here, we investigate the effect of the modified LDOS on LSC performance using first-principles simulations of Maxwell's equations in two realistic nanocavity LSC designs (Fig. 1, insets). After establishing a link between photonic LDOS and LSC performance, we use finite difference time domain (FDTD) simulations to show that a nanocavity LSC can increase the flux of waveguided luminescence photons by up to 30% over a conventional LSC. Finally, we assess the maximum theoretical performance gains from LDOS engineering in the LSC.First, we define a metric of LSC performance, con- * Electronic address: vwood@ethz.ch nect the performance metric to the photonic LDOS, and determine the conditions under which LSC performance comparisons can be made on the basis of the photonic LDOS. Luminescence photons are spontaneously emitted into one of many photonic modes of the LSC. These can be divided into two groups based on the wavevector in the LSC plane (k ): non-waveguided (ω ≥ c|k |) and total internally reflected (TIR, ω < c|k |) modes. In conventional LSCs, lumophore-filled w...

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“…Experimentally, this regime corresponds to either small LSCs or LSCs containing lumophores with small reabsorption, which has been demonstrated by exploiting Förster resonant energy transfer or intersystem crossing [2]. Eq.…”

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Nanophotonic luminescent solar concentrators

Rousseau

Wood

2013

Applied Physics Letters

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“…The first effect results from partial overlap of the absorption and emission spectra of the luminophore. This overlap can be reduced with materials (for example, semiconductor quantum dots) 14,15 that have large Stokes shifts, or with alternative conversion processes based on near-field energy transfer 16 or phosphorescence 17 . The waveguide losses can be decreased by increasing the difference between the index of refraction of the LSC material and its surroundings, and by engineering the structures to avoid scattering.…”

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Flexible concentrator photovoltaics based on microscale silicon solar cells embedded in luminescent waveguides

et al. 2011

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unconventional methods to exploit monocrystalline silicon and other established materials in photovoltaic (PV) systems can create new engineering opportunities, device capabilities and cost structures. Here we show a type of composite luminescent concentrator PV system that embeds large scale, interconnected arrays of microscale silicon solar cells in thin matrix layers doped with luminophores. Photons that strike cells directly generate power in the usual manner; those incident on the matrix launch wavelength-downconverted photons that reflect and waveguide into the sides and bottom surfaces of the cells to increase further their power output, by more than 300% in examples reported here. unlike conventional luminescent photovoltaics, this unusual design can be implemented in ultrathin, mechanically bendable formats. Detailed studies of design considerations and fabrication aspects for such devices, using both experimental and computational approaches, provide quantitative descriptions of the underlying materials science and optics.

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“…There is currently a renewed interest in this technology due to the availability of advanced materials (Ziessel et al, 2005;Currie et al, 2008;Mulder et al, 2009;Brühwiler et al, 2009;Earp et al, 2004) and sophisticated models to simulate the photon transport (Goldschmidt et al, 2008(Goldschmidt et al, , 2009. Major obstacles to be overcome are: limited stability of the luminescent species, high self-absorption, and poor knowledge of the parameters governing the efficiency 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 61 62 63 64 65 (Rowan et al, 2008).…”

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confidence: 99%