Fine line Al printing on narrow point contact opening for front side metallization

Tsuji, Kazuhiko; Suzuki, Shota; Morishita, N.; Kuroki, Takashi; Nakahara, Masahiro; Dhamrin, M.; Peng, Zih-Wei; Bück, Thomas; Usami, Noritaka

doi:10.1063/1.5123846

Cited by 10 publications

(7 citation statements)

References 9 publications

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“…Printing narrow Al contacts (here 50 µm width) with good electrical properties and aligning them with respect to the laser contact openings in industrial production is another challenge, and requires further development. It is interesting to note that Al fingers as narrow as 50 µm were recently reported 63,64 . A further challenge is the reliable and, under industrial environment (automated handling, no cleanroom atmosphere), robust passivation of a lightly doped textured surface.…”

Section: Resultsmentioning

confidence: 63%

Simulation-based roadmap for the integration of poly-silicon on oxide contacts into screen-printed crystalline silicon solar cells

Kruse

Schäfer

Haase

et al. 2021

Sci Rep

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We present a simulation-based study for identifying promising cell structures, which integrate poly-Si on oxide junctions into industrial crystalline silicon solar cells. The simulations use best-case measured input parameters to determine efficiency potentials. We also discuss the main challenges of industrially processing these structures. We find that structures based on p-type wafers in which the phosphorus diffusion is replaced by an n-type poly-Si on oxide junction (POLO) in combination with the conventional screen-printed and fired Al contacts show a high efficiency potential. The efficiency gains in comparsion to the 23.7% efficiency simulated for the PERC reference case are 1.0% for the POLO BJ (back junction) structure and 1.8% for the POLO IBC (interdigitated back contact) structure. The POLO BJ and the POLO IBC cells can be processed with lean process flows, which are built on major steps of the PERC process such as the screen-printed Al contacts and the $$\text{Al}_\text{2 }\text{O}_\text{3 }/\text{SiN }$$ Al 2 O 3 / SiN passivation. Cell concepts with contacts using poly-Si for both polarities ($$\text{POLO}^2$$ POLO 2 -concepts) show an even higher efficiency gain potential of 1.3% for a $$\text{POLO}^2$$ POLO 2 BJ cell and 2.2% for a $$\text{POLO}^2$$ POLO 2 IBC cell in comparison to PERC. For these structures further research on poly-Si structuring and screen-printing on p-type poly-Si is necessary.

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Section: Resultsmentioning

confidence: 63%

Simulation-based roadmap for the integration of poly-silicon on oxide contacts into screen-printed crystalline silicon solar cells

Kruse

Schäfer

Haase

et al. 2021

Sci Rep

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“…The J 0,Al value of 2800 fA cm − 2 chosen here is significantly higher than the values reported in recent publications on PERC cells. [ 16,20 ] A possible reason for such a high value is a too thin p + ‐type layer that we observe in the cross‐sectional SEM image of a point contact shown in Figure .…”

Section: Resultsmentioning

confidence: 94%

“…Figure shows a set of four simulation results that we use to estimate J 0 in the metallized areas. As a starting point, we use 600 fA cm − 2 for J 0,Al as recently measured by Tsuji et al [ 16 ] and 9 fA cm − 2 for J 0,Ag which equals as measured J 0 value of nonmetallized area at the rear side. This cell has an efficiency of 23.5% and an open‐circuit voltage of 722 mV as shown in Figure 5 and thus indicates the high efficiency potential of the POLO BJ when fully mastering the challenges of screen printing.…”

Section: Resultsmentioning

confidence: 99%

A 22.3% Efficient p‐Type Back Junction Solar Cell with an Al‐Printed Front‐Side Grid and a Passivating n⁺‐Type Polysilicon on Oxide Contact at the Rear Side

et al. 2020

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The fabrication of a silicon solar cell on 6 in. pseudo‐square p‐type Czochralski grown silicon wafers featuring poly‐Si‐based passivating contacts for electrons at the cell rear side and screen‐printed aluminum fingers at the front side is demonstrated. The undiffused front surface is passivated with an Al2O3/SiNx stack, and the rear surface is covered with a thin oxide/n+‐poly‐Si/Al2O3/SiNx layer system, contacted by screen‐printed silver fingers. A loss analysis shows that the recombination losses at the metal contacts on both cell sides dominate the total energy losses. A voltage of 700 mV as the highest open‐circuit voltage from a batch of seven cells is achieved, and the best cell efficiency is 22.3%, independently confirmed.

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“…In this work, we therefore focus on the influence of the Al‐p + contact on the cell efficiency. The recombination and resistance properties of local Al‐p + contacts are analyzed in various works 18,19 . The values differ a lot, which is due to the different paste compositions, process conditions, and methods used for the parameter extraction.…”

Section: Introductionmentioning

confidence: 99%

Fully screen‐printed silicon solar cells with local Al‐p⁺ and n‐type POLO interdigitated back contacts with a V_OC of 716 mV and an efficiency of 23%

Haase

Min

Hollemann

et al. 2021

Progress in Photovoltaics

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We demonstrate the fabrication of a fully screen‐printed p‐type silicon solar cell with local hole‐collecting Al‐alloyed (Al‐p+) contacts with a record open circuit voltage of 716 mV. The solar cell is fabricated by using almost the same process equipment as PERC cells. One of the dominant recombination losses in PERC cells is the recombination in the passivated and in the contacted emitter regions that so far limit the open circuit voltage to values below 700 mV. We eliminate these loss channels by substituting the P‐diffused emitter by a passivating n‐type poly‐Silicon on Oxide (nPOLO) contact. We place this contact on the rear side because of its otherwise strong parasitic absorption. The Al‐p+ contacts are also located at the rear side to avoid front‐side shading. This results in a POLO‐IBC cell structure. The efficiency of the best cell so far is 23.0% with a designated area of 4 cm2 fabricated on a M2‐sized wafer. Scanning electron microscopy reveals an Al‐p+ thickness of less than 3.3 μm and only a few 100 nm at the contact ends, which is less than the 5 μm typically for optimized Al‐p+ contacts. A comparison of measured and simulated current‐voltage curves over a variation of the contact fraction extracts a high saturation current density of the Al‐p+ contact of J0‐Al ‐p+ = 2,250 fA cm−2 for the current screen‐print conditions and Al‐paste causing an absolute efficiency loss of 0.5%abs. The recombination at the AlOx/SiNy surface and the shunt resistance limits the cell by 0.6%abs each.

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Fine line Al printing on narrow point contact opening for front side metallization

Cited by 10 publications

References 9 publications

Simulation-based roadmap for the integration of poly-silicon on oxide contacts into screen-printed crystalline silicon solar cells

Simulation-based roadmap for the integration of poly-silicon on oxide contacts into screen-printed crystalline silicon solar cells

A 22.3% Efficient p‐Type Back Junction Solar Cell with an Al‐Printed Front‐Side Grid and a Passivating n⁺‐Type Polysilicon on Oxide Contact at the Rear Side

Fully screen‐printed silicon solar cells with local Al‐p⁺ and n‐type POLO interdigitated back contacts with a V_OC of 716 mV and an efficiency of 23%

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Fine line Al printing on narrow point contact opening for front side metallization

Cited by 10 publications

References 9 publications

Simulation-based roadmap for the integration of poly-silicon on oxide contacts into screen-printed crystalline silicon solar cells

Simulation-based roadmap for the integration of poly-silicon on oxide contacts into screen-printed crystalline silicon solar cells

A 22.3% Efficient p‐Type Back Junction Solar Cell with an Al‐Printed Front‐Side Grid and a Passivating n+‐Type Polysilicon on Oxide Contact at the Rear Side

Fully screen‐printed silicon solar cells with local Al‐p+ and n‐type POLO interdigitated back contacts with a VOC of 716 mV and an efficiency of 23%

Contact Info

Product

Resources

About

A 22.3% Efficient p‐Type Back Junction Solar Cell with an Al‐Printed Front‐Side Grid and a Passivating n⁺‐Type Polysilicon on Oxide Contact at the Rear Side

Fully screen‐printed silicon solar cells with local Al‐p⁺ and n‐type POLO interdigitated back contacts with a V_OC of 716 mV and an efficiency of 23%