24.58% total area efficiency of screen-printed, large area industrial silicon solar cells with the tunnel oxide passivated contacts (i-TOPCon) design

Chen, Daming; Chen, Yifeng; Wang, Zigang; Gong, Jian; Liu, Chengfa; Zou, Yang; He, Yu Ting; Wang, Yao; Yuan, Ling; Lin, Wei; Xia, Rui; Yin, Li; Zhang, Xueling; Xu, Guanchao; Yang, Yang; Shen, Hui; Zhu, Feng; Altermatt, Pietro P.; Verlinden, Pierre J.

doi:10.1016/j.solmat.2019.110258

Cited by 193 publications

(121 citation statements)

References 22 publications

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“…Since a photoconversion efficiency (PCE) over 25% is reported, the tunnel oxide passivated contact (TOPCon) solar cell structure 1 and more generally the doped polycrystalline silicon/silicon oxide (poly-Si/SiO x ) stack such as SIPOS 2 or POLO 3,4 have gained interest with already industrialized processes presenting an impressive median PCE close to 24%. 5 For both-side contacted solar cells, the best performance at industrial level, with a PCE about 24.6%, 5,6 are remarkably close to the best PCE at research level, reported at 25.8% for a TOPCon structure 1 and at 25.1% for a HIT heterojunction structure. 7 Further improvements are expected by employing also a TOPCon structure for the boron-doped (p-type) front side instead of the boron-diffused emitter, to limit the number of high-temperature processes, and thus the impurities introduced over the surface.…”

Section: Introductionmentioning

confidence: 53%

Role of silicon surface, polished 〈100〉 and 〈111〉 or textured, on the efficiency of double‐sided TOPCon solar cells

Lozac’h

Nunomura

2020

Progress in Photovoltaics

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We investigate the role of the silicon surface and orientation on double‐sided TOPCon solar cells properties. The solar cells of front and rear, (p) and (n), poly‐Si/SiOx stack, fabricated on polished surfaces oriented 〈100〉 and 〈111〉 and pyramid textured surfaces, are characterized as a function of the thickness of an ultrathin SiOx layer, controlled at atomic scale from one‐ to four‐cycle atomic layer deposition (ALD). Our findings underline that the optimized thickness of the ultrathin SiOx is about 1.1 ± 0.1 nm, corresponding to a two‐cycle ALD, regardless of the surface and orientation of the c‐Si substrate. The open‐circuit voltage is about 10 mV higher on the polished 〈100〉‐oriented surface, associated with lower defect density at the interface of SiOx/c‐Si. On the other hand, the contact resistance is much lower, about 0.45 Ω/cm2, on the polished 〈111〉‐oriented surface. On textured surfaces, we demonstrate a photoconversion efficiency of 19.1% for the double‐sided TOPCon structure strictly for a SiOx thickness with two‐cycle ALD, which underlines the importance of the ALD technique for the precise control of the ultrathin SiOx thickness on textured surface.

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Section: Introductionmentioning

confidence: 53%

Role of silicon surface, polished 〈100〉 and 〈111〉 or textured, on the efficiency of double‐sided TOPCon solar cells

Lozac’h

Nunomura

2020

Progress in Photovoltaics

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“…Therefore, the fabrication of TOPCon on a rough surface would prevent blister formation. Indeed, recent research in the industry showed that industrial TOPCon solar cells can be fabricated using a textured back surface 3 . TOPCon fabrication on a textured back surface would also be beneficial for bifacial solar-cell applications 3 .…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, recent research in the industry showed that industrial TOPCon solar cells can be fabricated using a textured back surface 3 . TOPCon fabrication on a textured back surface would also be beneficial for bifacial solar-cell applications 3 . Figure 6 shows the evolution of implied V oc of the TOPCons fabricated on the CMP-treated, KOH-etched, and pyramid-textured c-Si surfaces.…”

Section: Resultsmentioning

confidence: 99%

“…The passivated emitter and rear contact (PERC) structure is a substantial upgrade over the conventional back surface field (BSF) structure and is employed in the industry as a new standard 2 . However, the recombination loss at the metal contacts is expected to be a major problem once the conversion efficiency reaches 23% 3 . Therefore, passivating contacts are spotlighted as an important research topic to realise a technical improvement in solar-cell technology.…”

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confidence: 99%

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Formation and suppression of hydrogen blisters in tunnelling oxide passivating contact for crystalline silicon solar cells

Choi

Kwon

Min

et al. 2020

Sci Rep

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the formation of hydrogen blisters in the fabrication of tunnelling oxide passivating contact (topcon) solar cells critically degrades passivation. in this study, we investigated the formation mechanism of blisters during the fabrication of topcons for crystalline silicon solar cells and the suppression of such blisters. We tested the effects of annealing temperature and duration, surface roughness, and deposition temperature on the blister formation, which was suppressed in two ways. first, topcon fabrication on a rough surface enhanced adhesion force, resulting in reduced blister formation after thermal annealing. Second, deposition or annealing at higher temperatures resulted in the reduction of hydrogen in the film. A sample fabricated through low-pressure chemical vapor deposition at 580 °C was free from silicon-hydrogen bonds and blisters after the TOPCon structure was annealed. Remarkably, samples after plasma-enhanced chemical vapor deposition at 300, 370, and 450 °C were already blistered in the as-deposited state, despite low hydrogen contents. Analysis of the hydrogen incorporation, microstructure, and deposition mechanism indicate that in plasma-enhanced chemical vapor deposition (pecVD) deposition, although the increase of substrate temperature reduces the hydrogen content, it risks the increase of porosity and molecular-hydrogen trapping, resulting in even more severe blistering.

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“…[ 1–5 ] Currently many research groups work on passivated contacts based on polycrystalline Si on oxide (POLO) or related junction schemes, applying different approaches for their implementation into industrial solar cells. [ 6–9 ] One approach is to apply nonpatterned POLO contacts for both polarities on the cell front‐ and rear side. [ 10–17 ] As poly‐Si layer on the top of this cell concept should be less than 20 nm to avoid parasitic absorption and therefore has high sheet resistances (above 1000 Ω sq −1 ), [ 10 ] a highly conductive and transparent layer (transparent conductive oxides [TCO]) on top of the poly‐Si needs to ensure the required lateral conductivity for the transport of charge carriers toward the metallization grid on the front side.…”

Section: Introductionmentioning

confidence: 99%

Ultra‐Thin Poly‐Si Layers: Passivation Quality, Utilization of Charge Carriers Generated in the Poly‐Si and Application on Screen‐Printed Double‐Side Contacted Polycrystalline Si on Oxide Cells

et al. 2020

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Herein, the various measures to improve the efficiency of large‐area screen‐printed double‐side contacted polycrystalline Si on oxide (POLO)‐cells are experimentally demonstrated. The short‐circuit current density Jsc increases by 0.6 mA cm−2 upon reducing the thickness of poly‐Si from 25 to 10 nm due to the reduction of the parasitic absorption in the poly‐Si layer at the textured front side of the cell. Additionally, it is shown for the first time that the minority carriers generated by light absorbed in the poly‐Si layer can at least partially be transferred into the crystalline Si base. Remarkably high implied open‐circuit voltage Voc,impl values are achieved with n‐type cell precursors by introducing an hydrogenation step by AlxOy after reducing the poly‐Si thickness, and by an additional annealing step after sputtering of transparent conductive oxides (TCOs). All cell precursors show Voc,impl values of up to 740 mV independent of the poly‐Si thickness. A reduction in the open‐circuit voltage Voc is observed during back‐end processing to 728 mV as measured on the final cells. A certified cell energy conversion efficiency of 22.3% is reported.

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24.58% total area efficiency of screen-printed, large area industrial silicon solar cells with the tunnel oxide passivated contacts (i-TOPCon) design

Cited by 193 publications

References 22 publications

Role of silicon surface, polished 〈100〉 and 〈111〉 or textured, on the efficiency of double‐sided TOPCon solar cells

Role of silicon surface, polished 〈100〉 and 〈111〉 or textured, on the efficiency of double‐sided TOPCon solar cells

Formation and suppression of hydrogen blisters in tunnelling oxide passivating contact for crystalline silicon solar cells

Ultra‐Thin Poly‐Si Layers: Passivation Quality, Utilization of Charge Carriers Generated in the Poly‐Si and Application on Screen‐Printed Double‐Side Contacted Polycrystalline Si on Oxide Cells

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