Process challenges of high-performance silicon heterojunction solar cells with copper electrodes

Yu, Jian; Bai, Yu; Li, Junjun; Qiu, Qingqing; Chen, Tao; Huang, Yuelong; Yu, Junsheng; Liao, Jiaxuan

doi:10.1016/j.solmat.2022.112057

Cited by 7 publications

(4 citation statements)

References 28 publications

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“…They found that solar cells with poor peel force exhibited deteriorated adhesion due to the presence of these voids. The authors attributed the formation of voids to the partial corrosion of the copper seed layer in a copper sulfate solution with a very low pH (hydrogen ion concentration) [33]. In contrast, in the current study, no voids were observed at the interface between the copper seed and ITO layers, and it was difficult to detect any voids at the interface between the electroplating copper and the copper seed layer.…”

Section: Fwhm Of Different Maximacontrasting

confidence: 91%

See 1 more Smart Citation

Study of Microstructure and Mechanical Properties of Electrodeposited Cu on Silicon Heterojunction Solar Cells

Jing¹,

Shan²,

Huang³

et al. 2023

Metals

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This study investigated the use of a pure copper seed layer to improve the adhesion strength and reduce the residual stress of electroplated copper films for heterojunction technology in crystalline solar cells. The experiment involved depositing a copper seed layer and an indium tin oxide (ITO) layer on textured silicon using sputtering. This resulted in the formation of a Cu(s)/ITO/Si structure. Following this step, a 10 µm thick copper layer was electroplated onto the Cu(s)/ITO/Si structure. Various characterization techniques were employed to evaluate the electroplated copper films’ microstructures, residual stress, and adhesion strength. The microstructures of the films were examined using a scanning transmission electron microscope (STEM), revealing a twin structure with a grain size of approximately 1 µm. The residual stresses of the as-deposited and annealed samples were measured using an X-ray diffractometer (XRD), yielding values of 76.4 MPa and 49.1 MPa, respectively. The as-deposited sample exhibited higher tension compared to the annealed sample. To assess the adhesion strength of the electroplated copper films, peel-off tests were conducted at a 90° angle with a constant speed of 30 mm/min. The peel force, measured in units of N/mm, was similar for both the as-deposited and annealed samples. Specifically, the peel force for electroplating copper on the copper seed layer on the ITO was determined to be 2.6 N/mm for the maximum value and 2.25 N/mm for the average value. This study demonstrated that using a pure copper seed layer during electroplating can improve adhesion strength and reduce residual stress in copper films for heterojunction technology in crystalline solar cells. These findings contribute to the development of more reliable and efficient solar-cell-manufacturing processes.

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Section: Fwhm Of Different Maximacontrasting

confidence: 91%

“…Metals 2023, 13, x FOR PEER REVIEW 11 of 13 low pH (hydrogen ion concentration) [33]. In contrast, in the current study, no voids were observed at the interface between the copper seed and ITO layers, and it was difficult to detect any voids at the interface between the electroplating copper and the copper seed layer.…”

Section: Fwhm Of Different Maximacontrasting

confidence: 89%

Study of Microstructure and Mechanical Properties of Electrodeposited Cu on Silicon Heterojunction Solar Cells

Jing¹,

Shan²,

Huang³

et al. 2023

Metals

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“…However, on module level this seems to have ignorable influence. [ 33 ] For group 2, the probable uncomplete etching of the Ti layer on the ITO may be responsible for the lower short‐circuit current j sc (−0.3 mA cm −2 ) reached with inkjet patterning. The relatively high j sc , V oc , and FF reached prove that it is possible with our plating approach to avoid shunts or parasitic Cu deposition.…”

Section: Resultsmentioning

confidence: 99%

Atomic Force Microscopy Analysis of Aluminum Layer Properties and Correlation to Masking Functionality in Copper Plating Metallization for Solar Cells

et al. 2023

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The native AlOx grown on a thin sputtered aluminum layer can be used as mask for electroplating copper, e.g., for metallizing silicon heterojunction (SHJ) solar cells. Effects that influence the masking quality for selective electroplating are studied herein. Atomic force microscopy characterization in PeakForce mode highlights the presence of some insulation defects in the native AlOx due to local contamination, pinholes, or tunneling currents. A focused ion beam/scanning electron microscopy analysis is further conducted to understand some defects in detail. The AlOx insulation can be improved by adsorbing a self‐assembled monolayer, which is mainly required along the process sequence to adjust the surface wetting of the Al for optimal NaOHaq printing. The mask quality and complete metallization sequence for solar cells are demonstrated on industrial SHJ precursors. Inkjet‐ and FlexTrail‐printing of NaOHaq are shown to be suitable to pattern the Al layer. Promising conversion efficiency comparable to screen‐printing reference is reached on large area.

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“…All these factors restrict the practical application of copper paste. In recent studies, some low-temperature sintering copper pastes with improved antioxidation were developed to print on soft substrates for flexible and wearable electronics. ,, Besides, for the power electronic devices (power chips for electric vehicles, energy storage, data centers, and solar cells), which require printing copper thick film electrodes on inorganic substrates (e.g., SiC, Si, GaN, AlN, Al 2 O 3 , etc., shown in Scheme ) where the dense sintering at relatively high temperature is essential to improve stability. , Preventing oxidation of copper electrodes during high sintering temperatures or long-term working temperatures of devices seems more challenging than low-temperature sintering copper electrodes.…”

Section: Introductionmentioning

confidence: 99%

Constructing Artificial Glass Nanobarrier Layer on Copper Spheres with Robust Antioxidation Properties for Printable Electrode

Jiang,

Yu,

et al. 2023

Chem. Mater.

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Copper-containing electronic pastes with the merits of low cost and high conductivity have been actively investigated for preparing conductive electrodes for printable electronics. However, oxidation of copper electrodes in the ambient atmosphere deteriorates devices and restricts their practical applications. Here, we designed an artificial glass nanobarrier layer on copper spheres to improve the antioxidation properties by blocking further oxidation. Specifically, a non-aqueous sol–gel method was applied to synthesize zinc borosilicate glass nanolayer-coated copper spheres with various diameters from 200 nm to 10 μm with zinc borosilicate glass nanolayer (Cu@ZBS). The Cu@ZBS-based copper pastes were screen printed on the silicon wafer and low-temperature co-fired ceramic (LTCC), demonstrating low-sheet resistance (11 mΩ/□), strong adhesion, and long-term stability. Our study blazes the trail of applicating reliable Cu@glass core–shell materials to fabricating conductive electrodes in printable electronic devices.

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Process challenges of high-performance silicon heterojunction solar cells with copper electrodes

Cited by 7 publications

References 28 publications

Study of Microstructure and Mechanical Properties of Electrodeposited Cu on Silicon Heterojunction Solar Cells

Study of Microstructure and Mechanical Properties of Electrodeposited Cu on Silicon Heterojunction Solar Cells

Atomic Force Microscopy Analysis of Aluminum Layer Properties and Correlation to Masking Functionality in Copper Plating Metallization for Solar Cells

Constructing Artificial Glass Nanobarrier Layer on Copper Spheres with Robust Antioxidation Properties for Printable Electrode

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