Development of thin polysilicon layers for application in monoPoly™ cells with screen-printed and fired metallization

Padhamnath, Pradeep; Khanna, Anuradha; Nandakumar, Naomi; Nampalli, Nitin; Shanmugam, Vinodh; Aberle, Armin G.; Duttagupta, Shubham

doi:10.1016/j.solmat.2019.110358

Cited by 47 publications

(31 citation statements)

References 40 publications

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“…This further justifies the search for better approaches to metallization of passivated contacts. [ 6 ]…”

Section: Resultsmentioning

confidence: 99%

“…The primary damage of screen‐printed cells is visible in V oc and short circuit current J sc . The metal paste spiking through poly‐Si, damaging the intermediate oxide layer and contacting the c‐Si, resulting in high recombination, [ 6 ] can explain the drop in V oc and J sc .…”

Section: Resultsmentioning

confidence: 99%

“…Some commonly reported concerns pertaining to the conventional screen‐printed metallization on TOPCon are 1) higher specific contact resistivity (1.5–10 Ω cm) on thick (>150 nm) poly‐Si passivated contacts [ 5 ] and 2) increase of metal‐induced recombination with decreasing thickness of poly‐Si due to the metal spiking through the poly‐Si and coming in contact with the bulk c‐Si. [ 6 ]…”

Section: Introductionmentioning

confidence: 99%

“…Spiking of the metal paste through the poly‐Si layer drastically increases the J 0,met (recombination current at metal–silicon junction) due to poor shielding of recombination at metal contacts, resulting in a low open circuit voltage ( V oc ). [ 6 ] To prevent the penetration of fire‐through metal pastes all the way through to the c‐Si substrate, it becomes necessary either to keep the thickness of poly‐Si above 120 nm or use low temperature metallization techniques. [ 7–10 ] However, a thicker poly‐Si layer has two serious drawbacks—increased parasitic absorption and higher cost of ownership (COO).…”

Section: Introductionmentioning

confidence: 99%

“…[ 7–10 ] However, a thicker poly‐Si layer has two serious drawbacks—increased parasitic absorption and higher cost of ownership (COO). Parasitic absorption inflates with increasing poly‐Si thickness, resulting in the loss of short circuit current ( J sc ), [ 6,11,12 ] whereas the COO calculations reveal a jump of around 75% if the poly‐Si thickness is increased from 50 to 200 nm. [ 13 ] Hence, to keep the parasitic absorption and the cost of fabrication/ownership low, it becomes imperative and desirable that the thickness of the poly‐Si layer be reduced.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Laser Ablation and Ni/Cu Plating Approach for Tunnel Oxide Passivated Contacts Solar Cells with Variate Polysilicon Layer Thickness: Gains and Possibilities in Comparison to Screen Printing

Arya

Steinhauser

Gruebel

et al. 2020

Physica Status Solidi (a)

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Recombination of photo-generated charge carriers at metalsemiconductor junctions is a strong limiting factor in achieving high efficiencies for conventional c-Si solar cells [e.g., aluminum back scatter field, passivated emitter rear contact (PERC), etc.]. [1-3] This can be reduced by squeezing the metallized area fraction, but that results in an increase of fill-factor (FF) loses. A novel approach developed at Fraunhofer ISE, namely, tunnel oxide passivated contacts (TOPCon), attempts to counter this effect by implementing passivating contact structures to drastically reduce metal-semiconductor junction recombination. [1,2,4] Passivated contact layers, such as TOPCon, constitute an ultrathin (1-2 nm) silicon oxide (SiO x) layer grown over the bulk c-Si, which is further deposited upon with a highly doped poly-Si layer and finally capped with SiN x. Together they provide excellent passivation, enabling high implied open circuit voltage (iV oc) [2] and carrier selectivity. [2,4] Furthermore, the depletion zone field generated due to high doping of poly-Si also contributes to the passivation effect. Passivating contacts are, therefore, considered to be the next major technological upgrade in the solar cell technology. [3,4] However, forming metal contacts on TOPCon is still a challenge that requires further investigation and improvements. Some commonly reported concerns pertaining to the conventional screen-printed metallization on TOPCon are 1) higher specific contact resistivity (1.5-10 Ω cm) on thick (>150 nm) poly-Si passivated contacts [5] and 2) increase of metal-induced recombination with decreasing thickness of poly-Si due to the metal spiking through the poly-Si and coming in contact with the bulk c-Si. [6] Spiking of the metal paste through the poly-Si layer drastically increases the J 0,met (recombination current at metal-silicon junction) due to poor shielding of recombination at metal contacts, resulting in a low open circuit voltage (V oc). [6] To prevent the penetration of fire-through metal pastes all the way through to the c-Si substrate, it becomes necessary either to keep the thickness of poly-Si above 120 nm or use low temperature metallization techniques. [7-10] However, a thicker poly-Si layer has two serious drawbacks-increased parasitic absorption and higher cost of ownership (COO). Parasitic absorption inflates with increasing poly-Si thickness, resulting in the loss of short circuit current (J sc), [6,11,12] whereas the COO calculations reveal a jump of around 75% if the poly-Si thickness is increased from 50 to 200 nm. [13] Hence, to keep the parasitic absorption and the cost

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“…This further justifies the search for better approaches to metallization of passivated contacts. [ 6 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Laser Ablation and Ni/Cu Plating Approach for Tunnel Oxide Passivated Contacts Solar Cells with Variate Polysilicon Layer Thickness: Gains and Possibilities in Comparison to Screen Printing

Arya

Steinhauser

Gruebel

et al. 2020

Physica Status Solidi (a)

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Large‐area monoPoly solar cells on 110 μm thin c–Si wafers with a rear n⁺poly‐Si/SiO_x stack deposited by inline plasma‐enhanced chemical vapour deposition

Nandakumar

Rodriguez

Padhamnath

et al. 2022

Progress in Photovoltaics

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We present an overview of SERIS' monoPoly technology on screen-printed, M2-size (244.4 cm 2 ) n-type bifacial silicon solar cells with a rear n + :poly-Si/SiO x passivating contact stack, where the SiO x and n + :poly-Si layers are fabricated by single-side inline plasma-enhanced chemical vapour deposition (PECVD). We demonstrate the application of these stacks on thin ($110 μm) silicon wafers, giving an excellent open-circuit voltage of 707 mV and an externally verified cell efficiency of 23.2% using commercial screen-printed and fire-through metal pastes. A detailed power analysis is presented, with a breakdown of the voltage and current losses. Finally, we share the progress on standard wafers with an efficiency of 23.8% achieved and present the outlook for this technology with a selective passivating contact stack at the front and a full-area passivating contact stack at the rear.

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Influence of Plasma‐Enhanced Chemical Vapor Deposition Poly‐Si Layer Thickness on the Wrap‐Around and the Quantum Efficiency of Bifacial n‐TOPCon (Tunnel Oxide Passivated Contact) Solar Cells

Grübel

Nagel

Steinhauser

et al. 2021

Physica Status Solidi (a)

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In typical industrial processing of tunnel oxide passivated contact (TOPCon) solar cells, poly‐Si is deposited on the entire back of the cells. During the deposition process, a wrap‐around of poly‐Si onto the edges and the front side of the cells is virtually unavoidable if chemical vapor deposition processes are used. Plasma‐enhanced chemical vapor deposition (PECVD) is used to investigate very thin poly‐Si films and their effect on wrap‐around on bifacial TOPCon solar cells fabricated without wrap‐around etching. As a result, reduction of the poly‐Si thickness down to 30 nm significantly increases the shunt resistance, reduces the reverse bias current, and thus reduces the risk of hot spots as measured by IR imaging and microcharacterization by secondary electron microscopy. Electroplated metallization proves to be a suitable candidate for contacting such thin TOPCon layers, being less sensitive than screen‐printed metallization.

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Development of thin polysilicon layers for application in monoPoly™ cells with screen-printed and fired metallization

Cited by 47 publications

References 40 publications

Laser Ablation and Ni/Cu Plating Approach for Tunnel Oxide Passivated Contacts Solar Cells with Variate Polysilicon Layer Thickness: Gains and Possibilities in Comparison to Screen Printing

Laser Ablation and Ni/Cu Plating Approach for Tunnel Oxide Passivated Contacts Solar Cells with Variate Polysilicon Layer Thickness: Gains and Possibilities in Comparison to Screen Printing

Large‐area monoPoly solar cells on 110 μm thin c–Si wafers with a rear n⁺poly‐Si/SiO_x stack deposited by inline plasma‐enhanced chemical vapour deposition

Influence of Plasma‐Enhanced Chemical Vapor Deposition Poly‐Si Layer Thickness on the Wrap‐Around and the Quantum Efficiency of Bifacial n‐TOPCon (Tunnel Oxide Passivated Contact) Solar Cells

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Development of thin polysilicon layers for application in monoPoly™ cells with screen-printed and fired metallization

Cited by 47 publications

References 40 publications

Laser Ablation and Ni/Cu Plating Approach for Tunnel Oxide Passivated Contacts Solar Cells with Variate Polysilicon Layer Thickness: Gains and Possibilities in Comparison to Screen Printing

Laser Ablation and Ni/Cu Plating Approach for Tunnel Oxide Passivated Contacts Solar Cells with Variate Polysilicon Layer Thickness: Gains and Possibilities in Comparison to Screen Printing

Large‐area monoPoly solar cells on 110 μm thin c–Si wafers with a rear n+poly‐Si/SiOx stack deposited by inline plasma‐enhanced chemical vapour deposition

Influence of Plasma‐Enhanced Chemical Vapor Deposition Poly‐Si Layer Thickness on the Wrap‐Around and the Quantum Efficiency of Bifacial n‐TOPCon (Tunnel Oxide Passivated Contact) Solar Cells

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Large‐area monoPoly solar cells on 110 μm thin c–Si wafers with a rear n⁺poly‐Si/SiO_x stack deposited by inline plasma‐enhanced chemical vapour deposition