Optimized nano-textured interfaces for thin-film silicon solar cells: identifying the limit of randomly textured interfaces

Jäger, Klaus; Linssen, Dane N.; Isabella, Olindo; Zeman, Miro

doi:10.1117/12.2057596

Cited by 6 publications

(5 citation statements)

References 17 publications

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“…On the other hand, when the average slope of the surfaces becomes small and the density of flat regions increases, resulting in lower θ av , the light is preferentially scattered into smaller scattering angles (see blue and green lines). Jäger et al observed similar trends from optical simulations carried out using the scalar scattering theory . These simulations showed that the lateral feature size, which is proportional to l c , strongly influences the photocurrent of thin-film silicon solar cells when σ rms is kept constant (i.e., effectively changing the average slope for randomly textured morphologies, which corresponds to the ratio between σ rms and l c ).…”

Section: Light Scattering Propertiesmentioning

confidence: 69%

“…Jager et al observed similar trends from optical simulations carried out using the scalar scattering theory. 23 These simulations showed that the lateral feature size, which is proportional to l c , strongly influences the photocurrent of thin-film silicon solar cells when σ rms is kept constant (i.e., effectively changing the average slope for randomly textured morphologies, which corresponds to the ratio between σ rms and l c ). Our experimental results are in good agreement with the simulation trends.…”

Section: Light Scattering Propertiesmentioning

confidence: 98%

“…In this contribution, we provide a deeper overview of how the substrate morphology, especially the slope distributions of the substrates besides σ rms and correlation length (l c ), 23 affects light scattering, defective-region formation, crystalline growth, and thereby nc-Si:H solar cell performance. First of all, we characterize substrate morphologies using various parameters such as σ rms , l c , and surface slope distributions of substrates.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Substrate Morphology Slope Distributions on Light Scattering, nc-Si:H Film Growth, and Solar Cell Performance

Kim

Santbergen

Jäger

et al. 2014

ACS Appl. Mater. Interfaces

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Thin-film silicon solar cells are often deposited on textured ZnO substrates. The solar-cell performance is strongly correlated to the substrate morphology, as this morphology determines light scattering, defective-region formation, and crystalline growth of hydrogenated nanocrystalline silicon (nc-Si:H). Our objective is to gain deeper insight in these correlations using the slope distribution, rms roughness (σ(rms)) and correlation length (lc) of textured substrates. A wide range of surface morphologies was obtained by Ar plasma treatment and wet etching of textured and flat-as-deposited ZnO substrates. The σ(rms), lc and slope distribution were deduced from AFM scans. Especially, the slope distribution of substrates was represented in an efficient way that light scattering and film growth direction can be more directly estimated at the same time. We observed that besides a high σ(rms), a high slope angle is beneficial to obtain high haze and scattering of light at larger angles, resulting in higher short-circuit current density of nc-Si:H solar cells. However, a high slope angle can also promote the creation of defective regions in nc-Si:H films grown on the substrate. It is also found that the crystalline fraction of nc-Si:H solar cells has a stronger correlation with the slope distributions than with σ(rms) of substrates. In this study, we successfully correlate all these observations with the solar-cell performance by using the slope distribution of substrates.

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Section: Light Scattering Propertiesmentioning

confidence: 69%

Section: Light Scattering Propertiesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Effect of Substrate Morphology Slope Distributions on Light Scattering, nc-Si:H Film Growth, and Solar Cell Performance

Kim

Santbergen

Jäger

et al. 2014

ACS Appl. Mater. Interfaces

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“…Based on this we can state that the systematic relative error in the calculated current density is not higher than 10%. [35][36][37] Optical models of multi-layers representing the various PEC/PV congurations are constructed in ASA. Measured wavelength-dependent reective index, n(l), extinction coefficient, k(l) and thicknesses of the layers are used as the optical input data for the simulation.…”

Section: Analysis Of Spectral Utilizationmentioning

confidence: 99%

Gradient dopant profiling and spectral utilization of monolithic thin-film silicon photoelectrochemical tandem devices for solar water splitting

et al. 2015

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A cost-effective and earth-abundant photocathode based on hydrogenated amorphous silicon carbide (a-SiC:H) is demonstrated to split water into hydrogen and oxygen using solar energy. A monolithic a-SiC:H photoelectrochemical (PEC) cathode integrated with a hydrogenated amorphous silicon (a-SiC:H)/nano-crystalline silicon (nc-Si:H) double photovoltaic (PV) junction achieved a current density of À5.1 mA cm À2 at 0 V versus the reversible hydrogen electrode. The a-SiC:H photocathode used no hydrogen-evolution catalyst and the high current density was obtained using gradient boron doping. The growth of high quality nc-Si:H PV junctions in combination with optimized spectral utilization was achieved using glass substrates with integrated micro-textured photonic structures. The performance of the PEC/PV cathode was analyzed by simulations using Advanced Semiconductor Analysis (ASA) software.

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“…It was reported that these defective regions of nc-Si:H are formed more likely when the opening angle on the textured substrate (θ open ) is smaller than certain critical angles (110–135°). ,− The presence of these defective regions in nc-Si:H substantially reduces the open-circuit voltage ( V oc ) and fill factor (FF) of solar cells, leading to lower power conversion efficiency. , Thus, in order to ensure both high quality nc-Si:H growth and light scattering, gently textured surfaces that do not generate defective regions but still enable sufficient light scattering are needed. So far, the light scattering capability has been fairly well predicted by the root-mean-square roughness (σ rms ) and correlation length ( l c ) of the textured surfaces. ,− Both the σ rms and l c , however, only describe the height distribution of the substrates and the lateral feature size, respectively, in a statistical way. Consequently, the real morphology of substrates can be different even when they have the same σ rms and l c .…”

Section: Introductionmentioning

confidence: 99%

Quantification of Valleys of Randomly Textured Substrates as a Function of Opening Angle: Correlation to the Defect Density in Intrinsic nc-Si:H

Kim

Hänni

Schüttauf

et al. 2016

ACS Appl. Mater. Interfaces

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Optical and electrical properties of hydrogenated nanocrystalline silicon (nc-Si:H) solar cells are strongly influenced by the morphology of underlying substrates. By texturing the substrates, the photogenerated current of nc-Si:H solar cells can increase due to enhanced light scattering. These textured substrates are, however, often incompatible with defect-less nc-Si:H growth resulting in lower Voc and FF. In this study we investigate the correlation between the substrate morphology, the nc-Si:H solar-cell performance, and the defect density in the intrinsic layer of the solar cells (i-nc-Si:H). Statistical surface parameters representing the substrate morphology do not show a strong correlation with the solar-cell parameters. Thus, we first quantify the line density of potentially defective valleys of randomly textured ZnO substrates where the opening angle is smaller than 130° (ρ<130). This ρ<130 is subsequently compared with the solar-cell performance and the defect density of i-nc-Si:H (ρdefect), which is obtained by fitting external photovoltaic parameters from experimental results and simulations. We confirm that when ρ<130 increases the Voc and FF significantly drops. It is also observed that ρdefect increases following a power law dependence of ρ<130. This result is attributed to more frequently formed defective regions for substrates having higher ρ<130.

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Optimized nano-textured interfaces for thin-film silicon solar cells: identifying the limit of randomly textured interfaces

Cited by 6 publications

References 17 publications

Effect of Substrate Morphology Slope Distributions on Light Scattering, nc-Si:H Film Growth, and Solar Cell Performance

Effect of Substrate Morphology Slope Distributions on Light Scattering, nc-Si:H Film Growth, and Solar Cell Performance

Gradient dopant profiling and spectral utilization of monolithic thin-film silicon photoelectrochemical tandem devices for solar water splitting

Quantification of Valleys of Randomly Textured Substrates as a Function of Opening Angle: Correlation to the Defect Density in Intrinsic nc-Si:H

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