Abstract

For the optimization of solar‐to‐electricity conversion efficiency of luminescent solar concentrators (LSCs), luminophores are treated as isotropic emitters. As rod‐shaped nanocrystals are being developed, their anisotropic emission properties may be beneficial for LSC efficiency, as it is expected that escape cone losses can be reduced by proper alignment of nanorods (NRs). Herein, theoretical considerations and Monte Carlo ray‐tracing simulations are used to examine the effect of anisotropic emission of luminophores on LSC performance, using nonspherical nanoparticles. Three different nanoparticles are examined with different Stokes shift and with two different quantum yield (QY) values (QY = 1 and QY = 0.7). In the case of a rod‐shaped emitter with emission intensity distribution aligned perpendicular to the lightguide plane, escape cone losses can potentially be reduced to ≈9%, compared to 25.5% for isotropic emission. For more realistic anisotropic emitters, escape cone losses reduce to ≈19%. Nonetheless, it is found that the useful emission of isotropic quantum dots with low reabsorption is much larger than that of aligning anisotropic emitting NRs with high reabsorption. Hence, focus on reducing reabsorption loss yields larger improvements in LSC device efficiency than focus on aligned NRs.

Highlights

  • For the optimization of solar-to-electricity conversion efficiency of luminescent the 1980s, and the continuously reduced solar concentrators (LSCs), luminophores are treated as isotropic emitters

  • We are going to examine whether optimal alignment of nanocrystals, given their three types and quantum yield (QY), will potentially lead to higher luminescent solar concentrator (LSC) device efficiencies compared with nanocrystals with isotropic emission

  • In this research, the effects of reabsorption, QY, and emission anisotropy were investigated for different nanocrystals for use in LSC devices

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Summary

Escape Fraction for Anisotropic Emission Patterns—Theory

In which θc is the critical angle for total reflection in the lightguide material.[9,10] For an ordinary isotropic (spherical) emitter, IðθÞ is constant, so that Equation (1) simplifies to. Www.solar-rrl.com rod-shaped emitter with the dipole transition parallel to the long axis (see Figure 1a in the Supporting Information), the intensity distribution is IðθÞ ∝ sin θ in case the rod is aligned perpendicular to the plate (Ω 1⁄4 0°). If the rod is aligned parallel to the plate (Ω 1⁄4 90°) (Figure 1b in the Supporting Information), the escape fraction is. Another extreme is that of a dipole transition perpendicular to the long axis in case the rod is aligned perpendicular to the plate, which is represented by cos emission. It can be seen that the escape fraction for vertical rods is larger than for pure sin emitters and smaller than for the isotropic case up to Ω % 55°

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