Exact ray theory for the calculation of the optical generation rate in optically thin solar cells

Brandsrud, Maren Anna; Seim, Eivind; Lukács, Rozália; Köhler, Achim; Marstein, Erik Stensrud; Olsen, Espen; Blümel, R.

doi:10.1016/j.physe.2018.08.018

Cited by 7 publications

(13 citation statements)

References 49 publications

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“…This is because the incoming ray vector coincides with the interface normal, and thus there is no plane of incidence. For the exact one-dimensional case, 49 there are no separate Fresnel equations for TE and TM. This is because the incoming ray vector coincides with the interface normal, and thus there is no plane of incidence.…”

Section: A Classical Ray Tracingmentioning

confidence: 99%

Chaos: a new mechanism for enhancing the optical generation rate in optically thin solar cells

Seim

Lukács

Köhler

et al. 2019

Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VIII

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The photogenerated current of solar cells can be enhanced by light management with surface structures. For solar cells with optically thin absorbing layers, it is especially important to take advantage of this fact through light trapping. The general idea behind light trapping is to use structures, either on the front surface or on the back, to scatter light rays to maximize their path length in the absorber. In this paper, we investigate the potential of chaotic scattering for light trapping. It is well known that the trajectories close to the invariant set of a chaotic scatterer spend a very long time inside of the scatterer before they leave. The invariant set, also called the chaotic repeller, contains all rays of in nite length that never enter or leave the region of the scatterer. If chaotic repellers exist in a system, a chaotic dynamics is present in the scatterer. As a model system, we investigate an elliptical dome structure placed on top of an optically thin absorbing lm, a system inspired by the chaotic Bunimovich stadium. A classical ray-tracing program has been developed to classify the scattering dynamics and to evaluate the absorption e ciency, modeled with Beer-Lambert's law. We nd that there is a strong correlation between the enhancement of absorption e ciency and the onset of chaotic scattering in such systems. The dynamics of the systems was shown to be chaotic by their positive Lyapunov exponents and the noninteger fractal dimension of their scattering fractals.

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Section: A Classical Ray Tracingmentioning

confidence: 99%

Chaos: a new mechanism for enhancing the optical generation rate in optically thin solar cells

Seim

Lukács

Köhler

et al. 2019

Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VIII

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“…where r is the amplitude of the reflected plane wave, 8,9 while |r| 2 = R is the reflection probability of the system. When the refractive index is real for all films involved, |r| 2 = 1 and the absorption cross section σ a = 0.…”

Section: Optimization Of Absorption Cross Section For Thin-film Systementioning

confidence: 99%

“…The system has been simplified into a three-layered system with mirror (b). 8 The system has been simplified by replacing the layers with different doping with one single layer with experimentally determined refractive index. [20][21][22] n 0 indicates the refractive index of vacuum, n 0 = 1.…”

Section: Optimization Of Absorption Of Thin-film Solar Cellsmentioning

confidence: 99%

“…In order to study the effectiveness of the device, we evaluate the absorption cross section, σ a . 8,9 The absorption cross section is similar to the optical generation rate, 10 while the optical generation rate is taking into account a weighting by the solar spectrum. The system that is evaluated in our work is a one dimensional system where the incoming light is propagating towards the system where the propagation direction is perpendicular to the surface.…”

Section: Introductionmentioning

confidence: 99%

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Optimized solar cells based on changes in resonance structure as a function of the refractive index and the thickness

Brandsrud

Lukács

Blümel

et al. 2019

Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VIII

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In order to reduce costs, the solar cell industry is aiming at producing ever thinner solar cells. Structuring the surfaces of optically thin solar cells is important for avoiding excessive transmission-related losses and, hence, to maintain or increase their efficiency. Light trapping leading to longer optical path lengths within the solar cells is a well established field of research. In addition to this, other possible benefits of structured surfaces have been proposed. It has been suggested that nanostructures on the surface of thin solar cells function as resonators, inducing electric-field resonances that enhance absorption in the the energy-converting material. Further, coupling of electric field resonances in periodically structured solar cells may couple with each other thereby increasing the absorption of energy. A deeper understanding of the nature of the energy-conversion enhancement in surface-structured and thin solar cells would allow to design more targeted structures. Generally, efficiency enhancement may be evaluated by investigating the electric field and optimizing the optical generation rate. Here, we establish a model system consisting of multilayered solar cells in order to study resonances and coupling of resonances in a one-dimensional system. We show that resonances in energyconverting and non-energy converting layers exist. The coupling of resonances in the non-energy converting material and the energy-converting material is only possible for certain parameter ranges of thickness of the energy converting material and the imaginary part of the refractive index. We evaluate the resonances and the coupling of resonances in different thin-film systems and show how they affect the total absorption of energy in the energy converting layer. We show how resonances in non-absorbing layers can contribute to increasing the resonances in the absorbing layers. We optimize the parameters of the multilayered thin-film systems to achieve an increase in the amount of the absorbed energy. The optimization is also evaluated for an experimentally realizable thin-film solar cell.

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“…To study the effectiveness of the device, we evaluate the absorption efficiency, σ a . [9][10][11] To take into account the characteristics of the solar spectrum, absorption efficiency can be multiplied by the solar spectrum. The resulting quantity is called the optical generation rate.…”

Section: Introductionmentioning

confidence: 99%

Investigation of resonance structures in optically thin solar cells

et al. 2021

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To reduce costs, the solar cell industry aims at producing thinner solar cells.Structuring the surfaces of optically thin devices is important for avoiding transmission-related losses and, hence, increasing their efficiency. Light trapping leads to longer optical pathlengths and increased absorption of energy. In addition, resonances in the nanostructures enhance the absorption in the energy-converting material. Further, resonances in periodic structures may couple with each other and thereby increase the absorption. Here, we establish a model system consisting of a multilayered solar cell to study resonances and coupling of resonances in a onedimensional system. We show that resonances in energy-converting and nonenergy converting layers exist, evaluate the resonances and the coupling of resonances in different thin-film systems, and show how they affect the total absorption of energy in the energy-converting layer. We optimize the parameters of the multilayered thin-film systems to achieve an increase in the amount of the absorbed energy. We find that resonances in nonabsorbing material at the top may lead to absorption enhancement, while we cannot find any enhancement effect due to the coupling of resonances. © 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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Exact ray theory for the calculation of the optical generation rate in optically thin solar cells

Cited by 7 publications

References 49 publications

Chaos: a new mechanism for enhancing the optical generation rate in optically thin solar cells

Chaos: a new mechanism for enhancing the optical generation rate in optically thin solar cells

Optimized solar cells based on changes in resonance structure as a function of the refractive index and the thickness

Investigation of resonance structures in optically thin solar cells

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