Rapid thermal firing of screen printed contacts for large area crystalline silicon solar cells

Huljic, D.M.; Biro, Daniel; Preu, R.; Lüdemann, R.

doi:10.1109/pvsc.2000.915845

Cited by 11 publications

(4 citation statements)

References 4 publications

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“…Despite the relatively large particle size up to about 7 mm, the inks were successfully printed with the aerosol metal jet system. After conventional contact firing in a rapid thermal firing furnace, 13 the adhesion to the silicon surface was of high quality. Unexpectedly, the thin deposited layer even etched through the SiN X antireflection coating during the firing process, yielding a good electrical contact.…”

Section: Printing Resultsmentioning

confidence: 99%

Metal aerosol jet printing for solar cell metallization

Mette

Richter

Hörteis

et al. 2007

Progress in Photovoltaics

197

101

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Metal aerosol jet printing is a new non-contact direct-write technique for the front side metallization of highly efficient industrial silicon solar cells. With this technique the first layer of a two-layer contact structure is created. It features a low contact resistance and good mechanical adhesion to the silicon surface. The second layer is formed by light-induced silver plating (LIP) to increase the line conductivity. To form the first layer a metal-containing aerosol is created in the printer and focused via a second surrounding gas stream through a nozzle and deposited onto the substrate. The focussing gas avoids the contact between the aerosol and the nozzle tip. In addition, line widths significantly smaller than the outlet diameter of the nozzle tip can be reached. Fine and continuous lines with a width of 14 mm were printed using a metal organic ink. As the adhesion of these layers was not sufficient, a commercially available screen-printing paste for solar cell metallization was modified and tested. Monocrystalline silicon solar cells of 12Á5 cm T 12Á5 cm with an aluminum back surface field were processed, achieving energy conversion efficiencies up to 17Á8%.

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Section: Printing Resultsmentioning

confidence: 99%

Metal aerosol jet printing for solar cell metallization

Mette

Richter

Hörteis

et al. 2007

Progress in Photovoltaics

197

101

View full text Add to dashboard Cite

show abstract

“…Variation of the wafer thickness leads to considerable changes of the thermal mass during processing, which results in correspondingly varying peak wafer temperatures often reported for standard firing in infrared-heated conveyor belt furnaces. By means of rapid thermal firing with closed-loop temperature control based on calibrated pyrometry, 13 control of process temperature during contact firing can be significantly improved, and in particular, the firing process becomes independent of the thermal mass of the wafers. Hence, this reduces possible fill factor variations and ensures high-quality contacts, especially for laboratory epitaxial cells with strongly varying substrate thickness.…”

Section: Resultsmentioning

confidence: 99%

“…The solar cell contacts were fired by the rapid thermal firing technique in a single-wafer RTP furnace with a closed-loop temperature control based on calibrated pyrometry. 13 The epitaxial as well as the reference cells were fired by the same thermal firing cycle. Finally, edge isolation was carried out with a Nd:YAG laser.…”

Section: Solar Cell Processmentioning

confidence: 99%

Screen‐printed epitaxial silicon thin‐film solar cells with 13·8% efficiency

Rentsch

Bau

Huljic

2003

Progress in Photovoltaics

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Amidst the different silicon thin-film systems, the epitaxial thin-film solar cell represents an approach with interesting potential. Consisting of a thin active c-Si layer grown epitaxially on top of a low-quality c-Si substrate, it can be implemented into solar cell production lines without major changes in the current industrial process sequences. Within this work, $ 30-m-thick epitaxial layers on non-textured and highly doped monocrystalline Czochralski (Cz) and multicrystalline (mc) Si substrates have been prepared by CVD. Confirmed efficiencies of 13Á8% on Cz and 12Á3% on mc-Si substrates have been achieved by applying an industrial process scheme based on tube and in-line phosphorus diffusion, as well as screen-printed front and back contacts fired through a SiN x anti-reflection coating. An extensive solar cell characterisation, including infrared lock-in thermography and spectral response measurements is presented.

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“…It has been shown that firing of screen-printed contacts in an RTP system can result in a contact resistance as low as 10 -cm [7], though the resulting fill factor (FF) was only 0.724 on multicrystalline silicon, presumably due to junction leakage. Recently, the Design of Experiment technique has been implemented to optimize a rapid thermal firing (RTF) process resulting in FF as high as 0.782 on Cz Si and 0.774 on multicrystalline Si [8]. However, the influence of RTF on the bulk defect passivation of mc-Si solar cells, if any, was not identified.…”

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confidence: 99%

Improved string ribbon silicon solar cell performance by rapid thermal firing of screen-printed contacts

Yelundur

Rohatgi

Jeong

et al. 2002

IEEE Trans. Electron Devices

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Al-enhanced SiN-induced hydrogenation is implemented to improve the minority carrier lifetime in String Ribbon Si. Rapid cooling after the hydrogenation anneal is found to increase the spatially averaged relative lifetime enhancement by over 160% for String Ribbon Si samples with a spatially averaged as-grown lifetime of 2.9 s. Partial coverage of back surface by Al eliminates wafer bowing in 100 m thick substrates, but reduces the spatially averaged lifetime enhancement to below 100% because vacancy generation at the back surface is decreased. Rapid thermal firing (RTF) of screen-printed contacts, with high heating and cooling rates, is found to improve String Ribbon solar cell efficiency by an average of 1.2% absolute over lamp heated belt furnace contact firing. Light beam-induced current (LBIC) mapping and light biased or differential internal quantum efficiency (IQE) analysis show that the enhancement in cell performance is primarily due to an improved effective diffusion length and diffusion length uniformity, which are both a result of the improved retention of hydrogen at defects achieved during rapid cooling after contact firing. Screen-printed String Ribbon cells with independently confirmed efficiencies as high as 14.7% are achieved through an understanding and implementation of hydrogen passivation of defects. Index Terms-Hydrogen passivation, multicrystalline silicon (mc-Si), rapid thermal processing (RTP), ribbon silicon, silicon nitride. I. INTRODUCTION T HE U.S. Photovoltaics Industry Roadmap calls for the development of 18% manufacturable cells on low-cost crystalline silicon materials within the next eight to ten years [1]. To meet this target, the as-grown minority carrier lifetime in low-cost Si materials must be increased to over 20 s, and integrated with a high-quality surface passivation scheme, light trapping, a selective emitter, and high quality metallization, all achieved with manufacturable processing technologies.

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Rapid thermal firing of screen printed contacts for large area crystalline silicon solar cells

Cited by 11 publications

References 4 publications

Metal aerosol jet printing for solar cell metallization

Metal aerosol jet printing for solar cell metallization

Screen‐printed epitaxial silicon thin‐film solar cells with 13·8% efficiency

Improved string ribbon silicon solar cell performance by rapid thermal firing of screen-printed contacts

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