Maximum statistical increase of optical absorption in textured semiconductor films

Deckman, H. W.; Roxlo, C. B.; Yablonovitch, Eli

doi:10.1364/ol.8.000491

Cited by 95 publications

(50 citation statements)

References 7 publications

(11 reference statements)

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“…A Lambertian angular distribution of light is likely achieved after several internal reflections, but this approximation is crude for the first few bounces and is better suited to the analysis of thin-film devices with nanoscale textures. 9,47 We chose instead to employ a ray tracer to track rays inside the cell, obviating the need to assume an angular distribution function at all. For each internal reflection, the tracer knows the angle of incidence and can thus adopt the appropriate results from Fig.…”

Section: Simulation and Measurement Of Total Reflectancementioning

confidence: 99%

Infrared light management in high-efficiency silicon heterojunction and rear-passivated solar cells

Holman¹,

Filipič²,

Descoeudres³

et al. 2013

Journal of Applied Physics

286

207

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Silicon heterojunction solar cells have record-high open-circuit voltages but suffer from reduced short-circuit currents due in large part to parasitic absorption in the amorphous silicon, transparent conductive oxide (TCO), and metal layers. We previously identified and quantified visible and ultraviolet parasitic absorption in heterojunctions; here, we extend the analysis to infrared light in heterojunction solar cells with efficiencies exceeding 20%. An extensive experimental investigation of the TCO layers indicates that the rear layer serves as a crucial electrical contact between amorphous silicon and the metal reflector. If very transparent and at least 150 nm thick, the rear TCO layer also maximizes infrared response. An optical model that combines a ray-tracing algorithm and a thin-film simulator reveals why: parallel-polarized light arriving at the rear surface at oblique incidence excites surface plasmons in the metal reflector, and this parasitic absorption in the metal can exceed the absorption in the TCO layer itself. Thick TCO layers-or dielectric layers, in rear-passivated diffused-junction silicon solar cells-reduce the penetration of the evanescent waves to the metal, thereby increasing internal reflectance at the rear surface. With an optimized rear TCO layer, the front TCO dominates the infrared losses in heterojunction solar cells. As its thickness and carrier density are constrained by anti-reflection and lateral conduction requirements, the front TCO can be improved only by increasing its electron mobility. Cell results attest to the power of TCO optimization: With a high-mobility front TCO and a 150-nm-thick, highly transparent rear ITO layer, we recently reported a 4-cm 2 silicon heterojunction solar cell with an active-area short-circuit current density of nearly 39 mA/cm 2 and a certified efficiency of over 22%. V C 2013 American Institute of Physics. [http://dx

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Section: Simulation and Measurement Of Total Reflectancementioning

confidence: 99%

Infrared light management in high-efficiency silicon heterojunction and rear-passivated solar cells

Holman¹,

Filipič²,

Descoeudres³

et al. 2013

Journal of Applied Physics

286

207

View full text Add to dashboard Cite

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“…Here, we use the well-known conic problem of scattered fields from a metallic sphere in a vacuum space (shown in Ref [39]) to validate our models for MNPs. If an electric field of a uniform plane wave is polarized in the x direction, and is traveling along the z-axis, then the monostatic radar cross section can be expressed by (1) where r, E s , E i , λ, β, a, and H (2) are represent the range, scattered electric field, incident electric field, wavelength, wave propagation constant, radius of the metallic sphere, and spherical Hankel function, respectively. A plot of equation 1 as a function of the radius of the sphere is shown in Figure 6.…”

Section: Electromagnetic Field Analysis Of Mnpsmentioning

confidence: 99%

“…Fortunately, there are different methods to achieve such enhancement. For instance, applying a randomly textured layer inside the device is a standard approach to gain more effective scattered rays inside the device [2][3][4][5]. Additionally, introducing a periodic structure as a reflector to enable the increase of light path inside the absorber [6][7][8]; thus enhancing light absorption.…”

Section: Introductionmentioning

confidence: 99%

A three‐dimensional multiphysics modeling of thin‐film amorphous silicon solar cells

Ghahremani

Fathy

2015

Energy Science & Engineering

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A 3D multiphysics simulation toolbox for thin-film amorphous silicon solar cells has been developed. The simulation is rigorous and is based on developing three modules: first to analyze light propagation using electromagnetic techniques, second to account for charge generation and transportation based on the physics of the semiconductor device, and third including electrode modeling by applying electrostatic techniques. Published results of a P-I-N thin-film amorphous silicon solar cell fabricated on a thick glass and experimentally evaluated was used as a vehicle to validate our 3D multiphysics toolbox and demonstrate its capabilities. The toolbox utilizes COMSOL for solving the partial differential equations describing the three modules, and MATLAB to input data, control the solver, and provides the coupling between the three modules. The developed toolbox was used to investigate both the effect of embedding Metallic Nanoparticles (MNPs) and the impact of defects on the external quantum efficiency. The simulator, besides being rigorous, is suitable to model various types of solar cells (organic, inorganic, thick film, thin film, heterojunction, or plasmonic) as well. 521

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“…Deckman et al [57] were the first who experimentally demonstrated absorption enhancement factors of up to 12. The same authors also showed that the achievements were directly translated into 25% higher short-circuit currents [58], though extremely thick a-Si:H absorber layers around 1 µm were used in both studies.…”

Section: Fig 213mentioning

confidence: 99%

Diffractive Optics for Thin-Film Silicon Solar Cells

Schuster¹

2017

Springer Theses

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Thin-film silicon solar cells have the potential to convert sunlight into electricity at high efficiency, low cost and without generating pollutants. However, they need to become more competitive with conventional energy technologies by increasing their efficiency.One of the key efficiency limitations of using thin silicon absorber materials relates to the optical loss of low-energy photons, because the absorption coefficient of silicon decreases strongly for these low-energy photons in the red and nearinfrared, such that the absorption length becomes longer than the absorber layer thickness. If, in contrast, the incident light was redirected and trapped into the plane of the silicon slab, a thin-film could absorb as much light as a thick layer.Diffractive textures can not only efficiently scatter the low-energy photons, but are also able to suppress the reflection of the incident sunlight. In order to take advantage of the full benefits that textures can offer, I outline a simple layer transfer technique that allows the structuring of a thin-film independently from both sides, and use absorption measurements to show that structuring on both sides is favourable compared to structuring on one side only. I also introduce a figure-of-merit that can objectively and quantitatively assess the benefit of the structuring itself, which allows me to benchmark state-ofthe-art proposals and to deduce some important design rules. Minimising the parasitic losses, for example, is of critical importance, as the desired scattering properties are directly proportional to these losses. To study the impact of parasitics, I quantify the useful absorption enhancement of two different light trapping mechanisms, i.e. diffractive vs plasmonic, based on a fair and simple experimental comparison. The experiment demonstrates that diffractive light-trapping is a better choice for photovoltaic applications, because plasmonic structures accumulate the parasitical losses by multiple interactions with the trapped light.

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Maximum statistical increase of optical absorption in textured semiconductor films

Cited by 95 publications

References 7 publications

Infrared light management in high-efficiency silicon heterojunction and rear-passivated solar cells

Infrared light management in high-efficiency silicon heterojunction and rear-passivated solar cells

A three‐dimensional multiphysics modeling of thin‐film amorphous silicon solar cells

Diffractive Optics for Thin-Film Silicon Solar Cells

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