Progress in screen-printed metallization of industrial solar cells with SiOx/poly-Si passivating contacts

Padhamnath, Pradeep; Khanna, Anuradha; Balaji, Nagarajan; Shanmugam, Vinodh; Nandakumar, Naomi; Wang, Deng; Sun, Qian; Huang, Ming Chih; Huang, Shumei; Fan, Baobing; Ding, Bingbing; Aberle, Armin G.; Duttagupta, Shubham

doi:10.1016/j.solmat.2020.110751

Cited by 27 publications

(13 citation statements)

References 49 publications

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“…The main findings are in good agreement with other early investigations from our side [ 24 ] and other authors. [ 7,15,28–31 ] The comparison of both pastes for the same polysilicon thickness reveals that paste C forms a lower ohmic contact than paste F at T set = 840 °C firing, but at T set = 870 °C, the opposite holds true.…”

Section: Resultsmentioning

confidence: 99%

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Progress in p‐type Tunnel Oxide‐Passivated Contact Solar Cells with Screen‐Printed Contacts

et al. 2021

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Herein, an update on the work on high‐efficiency p‐type solar cells with p‐type‐passivating rear contacts formed by low‐pressure chemical vapor deposition and screen‐printed contacts is given. It is shown that thin polysilicon layers enable a high level of surface passivation but do show increased contact resistivity and especially contact recombination. Commercially available pastes and dependence of contact resistivity and contact recombination on polylayer thickness and firing set temperature are investigated. For 240 nm‐thick poly‐Si layers, the values down to 4 mΩ cm2 and 60 fA cm−2 are observed. For the presented process sequence, improved hydrogenation as one possibility to increase the passivation quality of the passivating contact structure is identified. Implementing all findings into a final solar cell, a maximum total area conversion efficiency of 21.2% is reported.

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Section: Resultsmentioning

confidence: 99%

“…As the n‐type passivating contact has some physical and technical advantages over the p‐type counterpart such as passivation quality or a more straightforward metallization by screen‐printed silver pastes, [ 5 ] most TOPCon solar cells are fabricated on n‐type wafers. [ 6–11 ]…”

Section: Introductionmentioning

confidence: 99%

Progress in p‐type Tunnel Oxide‐Passivated Contact Solar Cells with Screen‐Printed Contacts

et al. 2021

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“…Following this study, a contact resistivity of 2.7 mΩ cm 2 is presented for an 80-150 nm thick n þ LPCVD-deposited polysilicon, with screen printing of partially fire through paste in the work of Chang et al [14] Articles from Padhamnath et al from SERIS also show excellent J 0met value below 50 fA cm À2 with excellent contact resistivity below 2 mΩ cm 2 for ex situ-doped LPCVDdeposited polysilicon layers on top of a thin thermal oxide. [15,16] The J 0met values in this work were generated from their in-house developed software. This requires contact resistivity, sheet resistance, and the PL images of screen-printed metallized samples as input to the software.…”

Section: Doi: 101002/pssa202100243mentioning

confidence: 99%

Influence of Polysilicon Thickness on Properties of Screen‐Printed Silver Paste Metallized Silicon Oxide/Polysilicon Passivated Contacts

Chaudhary

Hoß

Lossen

et al. 2021

Physica Status Solidi (a)

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This work investigates how the thickness of the polysilicon layer and temperatures during contact sintering influence the properties of SiOx/polysilicon passivated contacts. The n+ polysilicon layers deposited by low‐pressure chemical vapor deposition (LPCVD) on top of a thin wet chemically grown interface oxide layer providing chemical and field‐effect passivation on n‐type monocrystalline silicon wafers are investigated. Three different polysilicon layer thicknesses of 50, 100, and 150 nm are considered in this work. A high level of passivation with implied Voc values above 735 mV and J01 below 5 fA cm−2 is obtained for symmetric lifetime test samples. These samples are used to investigate the interaction of the silver paste with the polysilicon layer at different fast firing peak temperatures. Reduction in polysilicon layer thickness leads to an increase in contact resistivity as well as in J0met. Excellent J0met values of the order of J01 with contact resistivity values below 2 mΩ cm2 are obtained for samples with polysilicon layers of 100 and 150 nm thickness.

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“…We inspect selected samples with scanning electron microscopy (SEM) after we remove the silver fingers completely. [ 6–9 ] For this, we etch the silver fingers in 69% nitric acid (HNO 3 ) at 95 °C for 10 min. Subsequently, etching in 5% hydrofluoric (HF) acid at room temperature for 5 min removes the interfacial glass layer.…”

Section: Figurementioning

confidence: 99%

“…However, it was reported that the screen-printed silver paste attacks the poly-Si layer during the firing step and deteriorates the passivation quality of polysilicon on oxide (POLO) contacts significantly. [6][7][8] This effect can be reduced by changing the chemistry of silver pastes, [8,9] by increasing the poly-Si layer thickness, [6,7] or by deepening the in-diffusion of phosphorus dopants from the poly-Si layer into wafers. [7,10,11] In this work, we evaluate the possibility to reduce this deterioration of the passivation quality by adjusting the SiN x capping layer thickness and the peak firing temperature.…”

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confidence: 99%

716 mV Open‐Circuit Voltage with Fully Screen‐Printed p‐Type Back Junction Solar Cells Featuring an Aluminum Front Grid and a Passivating Polysilicon on Oxide Contact at the Rear Side

et al. 2020

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This article reports the recent progress of p-type back junction solar cells featuring an aluminum front grid and an n þ-type passivating polysilicon on oxide (POLO) contact at the cell rear side. The best cell has an efficiency of 22.6% and an open-circuit voltage of 716 mV, independently confirmed by Institute for Solar Energy Research Hamelin (ISFH) CalTeC. The cell area is 244.5 cm 2. The increase in the SiN x capping layer thickness at the cell rear side reduces the deterioration of passivation quality of the POLO contact by screen-printed silver. This increases the open-circuit voltage by 22 mV compared with cells with a thinner nitride layer thickness. The investigation with scanning electron microscopy shows that the damage of the POLO contacts underneath the screen-printed metal contacts is avoided by increasing the SiN x capping layer thickness. A contact resistivity of 2 mΩ cm 2 is measured using the transfer length method.

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Progress in screen-printed metallization of industrial solar cells with SiOx/poly-Si passivating contacts

Cited by 27 publications

References 49 publications

Progress in p‐type Tunnel Oxide‐Passivated Contact Solar Cells with Screen‐Printed Contacts

Progress in p‐type Tunnel Oxide‐Passivated Contact Solar Cells with Screen‐Printed Contacts

Influence of Polysilicon Thickness on Properties of Screen‐Printed Silver Paste Metallized Silicon Oxide/Polysilicon Passivated Contacts

716 mV Open‐Circuit Voltage with Fully Screen‐Printed p‐Type Back Junction Solar Cells Featuring an Aluminum Front Grid and a Passivating Polysilicon on Oxide Contact at the Rear Side

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