Laser-based foil rear side metallization for crystalline silicon solar cells

Nekarda, Jan; Graf, M. B.; Rodofili, A.; Aßmus, W.; Preu, R.

doi:10.1117/12.929639

Cited by 15 publications

(18 citation statements)

References 4 publications

(6 reference statements)

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“…Therefore, the solar cells fabricated with rear aluminum foil electrodes presented slightly higher short-circuit current densities. This effect seems to be related to a thin gap of air embedded between the aluminum foil and the rear surface [12]. Thus, the operation of this structure as a back reflector is expected to be superior to that achieved with screen-printed aluminum layers.…”

Section: Discussionmentioning

confidence: 99%

“…The absorption of back-reflected photons of energy slightly above the band gap would increase during the additional pass through the whole wafer thickness. A plausible explanation of the improved internal reflectance when aluminum foils are used as a rear contact was given by Nekarda et al [12]. According to their work, a thin layer of embedded air remaining between the foil and the passivation layer can lead to a better back reflectance in the infrared region.…”

Section: Detailed Analysis Of Al Foil Electrodesmentioning

confidence: 99%

“…This strategy does not require any vacuum deposition or annealing step, which results in a cost reduction that could promote the laser-firing technique into the PV industry. The high potential of this approach has been demonstrated previously on a rear passivation stack of alumina and silicon oxide for conventionally diffused-emitter c-Si solar cells [12]. In this work the heterojunction emitter and a rear passivation structure based on amorphous silicon, along with the introduction of Al foil rear electrodes, lead to a simplified low-temperature fabrication process for high-efficiency silicon solar cells.…”

Section: Introductionmentioning

confidence: 96%

“…The laser-firing technique has excelled in the last years owing to its high potential and flexibility [9]. To date, different kinds of lasers [10] and alternative metallic sources [11] [12] have been successfully tested to produce laser-fired contacts (LFC) in complete solar cells. Conversion efficiencies over 20% [13] [14] were reported for a conventional diffused emitter, whereas in low-temperature heterojunction devices we have recently obtained efficiencies around 18% [15].…”

Section: Introductionmentioning

confidence: 99%

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Low Surface Recombination in Silicon-Heterojunction Solar Cells With Rear Laser-Fired Contacts From Aluminum Foils

Colina

Morales-Vilches

Voz

et al. 2015

IEEE J. Photovoltaics

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Abstract-In this work an approach to create laser-fired contacts from aluminum foils is studied on p-type silicon heterojunction solar cells. This alternative approach consists in the use of aluminum foils instead of evaporated layers as a metal source and rear electrode for the laser-firing process. A q-switched infrared laser (1064 nm) was employed to create the local point contacts. Quasi-Steady-State Photoconductance measurements evidenced a limited degradation in the surface passivation quality during the laser-firing process. Heterojunction solar cells fabricated with these rear contacts reached a best conversion efficiency of 18% with a remarkable opencircuit voltage of 690 mV. These values were very close to those of reference devices fabricated with evaporated aluminum layers. This result suggests a similar effect on the rear surface passivation by both contact strategies. However, external quantum efficiency curves revealed a better response of devices with a rear aluminum foil in the near infrared. Optical measurements indicate that this effect can be related to a higher internal reflection at the back surface. Consequently, laser-fired contacts from aluminum foils appear as a fast and convenient solution for the rear contact of high-efficiency silicon solar cells.

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Section: Discussionmentioning

confidence: 99%

Section: Detailed Analysis Of Al Foil Electrodesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Low Surface Recombination in Silicon-Heterojunction Solar Cells With Rear Laser-Fired Contacts From Aluminum Foils

Colina

Morales-Vilches

Voz

et al. 2015

IEEE J. Photovoltaics

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“…Conversion efficiencies above 20% have been already reported in conventional (diffused-emitter) solar cells incorporating rear laser-fired contacts (LFC) through different passivation layers [11]- [13]. Alternative metallic sources to produce laser-fired contacts have also been tested in completed devices [14], [15]. However, the variation of the wavelength of the laser used in this process has not been widely explored in heterojunction devices.…”

Section: Introductionmentioning

confidence: 99%

Study of the Surface Recombination Velocity for Ultraviolet and Visible Laser-Fired Contacts Applied to Silicon Heterojunction Solar Cells

Morales-Vilches

Voz

Colina

et al. 2015

IEEE J. Photovoltaics

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Abstract-In this work we investigate the effect of the laser-firing process on the back surface passivation of p-type silicon heterojunction solar cells. For that purpose, two different nanosecond laser sources radiating at ultraviolet (355 nm) and visible (532 nm) wavelengths are employed. Firstly, we optimize the laser-firing process in terms of the electrical resistance of locally diffused point contacts. Specific contact resistance values as low as 0.91 mΩ⋅cm 2 and 0.57 mΩ⋅cm 2 are achieved for the visible and ultraviolet laser sources, respectively. In addition, the impact of the laser-firing process on the rear surface passivation is studied by analyzing the internal-quantum-efficiency curves of complete devices. Low surface recombination velocities in the range of 300 cm/s are obtained for the ultraviolet laser with a 1% fraction of contacted area. This value increases to about 700 cm/s for the visible laser, which indicates a significantly higher recombination at the contacted area. The best heterojunction solar cells with rear laser-fired contacts are obtained for the ultraviolet laser and reached a 17.5% conversion efficiency.

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Modified laser‐fired contact process for efficient PERC solar cells

Choi

Jung

Park

et al. 2019

Progress in Photovoltaics

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A laser‐fired contact (LFC) process is one of the techniques for making local electrical contacts at the rear side of passivated emitter and rear cell (PERC) solar cells. In the LFC process, opening of the passivated dielectric layers and alloying of Si and Al need to be made in a single step laser process. For this reason, the LFC process is accompanied by the loss of Al and the laser damage to the Si wafer. In this study, we present a novel multistep LFC process combining the conventional LFC and laser‐induced forward transfer (LIFT) processes. The modified LFC scheme we proposed consists of three steps: (a) opening of the passivation layers and partial alloying of Al‐Si, (b) additional deposition of Al on the local contact holes, and (c) post laser firing of the transferred Al. Applying the modified LFC process to the PERC cells of 1.0 cm2 of area, we demonstrate the effective recombination velocity of the laser‐processed wafers can be remarkably reduced while maintaining the low contact resistance. The best of the PERC solar cell fabricated by the modified LFC process exhibited an efficiency of 19.5% while the conventional LFC‐PERC cell showed 18.6%. The efficiency gains of the modified LFC‐PERC cells was largely contributed by the enhanced open circuit voltage (Voc) and fill factor (FF).

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Laser-based foil rear side metallization for crystalline silicon solar cells

Cited by 15 publications

References 4 publications

Low Surface Recombination in Silicon-Heterojunction Solar Cells With Rear Laser-Fired Contacts From Aluminum Foils

Low Surface Recombination in Silicon-Heterojunction Solar Cells With Rear Laser-Fired Contacts From Aluminum Foils

Study of the Surface Recombination Velocity for Ultraviolet and Visible Laser-Fired Contacts Applied to Silicon Heterojunction Solar Cells

Modified laser‐fired contact process for efficient PERC solar cells

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